'He swears he hasn't got it.' Still no emotion, no direct eye contact as Jayden ran his fingers over the rough, cold stone.

'Why? Why would he have Lily's tooth? You think he's keeping it in a little jar somewhere as a souvenir? In a drawer, on a shelf, hanging on a chain round his neck?'

Jayden didn't react. 'Me and Harry moved on to the tooth subject after we dealt with the who's-the-daddy topic.'

'Oh, Jesus!' I didn't know what to say or to think, except that it was possible that this time Jayden had totally lost it. OK, so I've said before that Harry Embsay isn't my type. Remember how he blamed everyone the second he saw Paige lying badly injured in the stable yard, how he was always throwing his weight around, even way back when Saint Sam addressed the whole sixth form in the new library?

'What's he going to tell us that we don't already know?' Zara asked.

'Search me,' Harry said, huffing and puffing. 'But it had better be worth dragging me out of bed for.'

Harry is big and sulky and doesn't stay out of your personal space enough for my liking. He's athletic without any grace and it's brute strength, not balance and finesse, that allows him to yank on the reins and control Franklin when he gallops him through the woods and almost knocks me down.

'He denied everything,' Jayden told me in a flat, slightly slurred voice, speaking without moving his lips as if he didn't really want to let go of the words.

'Of course he did!' I spluttered. 'Lily wouldn't . . .'

Jayden tilted his head to one side then turned to look at me from under hooded lids. He waited.

'She wouldn't . . .' I began again.

Another memory wormed itself out of the deep recesses of my brain. It reappeared verbatim a conversation with Paige, in our room, sitting on our unmade beds.

Maybe the baby was a result of a one-night stand this had been my theory.

Unshockable Paige had been shocked and defended her dead friend's honour. 'Lily didn't do one night stands,' she'd insisted.

Then maybe a holiday romance a random waiter or beach bum?

'Lily didn't go on holiday this year.' Paige wouldn't even listen to my idle speculation as we tried to work out who was the baby's father.

'She didn't?' No luxury yacht, no penthouse suite overlooking the beach?

'No. She was in the UK, drifting, doing her own thing, staying away from her dad.'

'The tyrant.'

'Yeah,' Paige said the pre-accident Paige, the invincible Paige. 'She came to see me ride in the Burghley Horse Trials. That was late August. Harry Embsay and Guy Simons were there too.'

I drew in a sharp breath then let it out, felt my head swim as I computed what this might mean. 'Harry it could've been . . . Wait, Jayden I'm not sure!'

He stared at me then started to walk jerkily towards the daylight at the far end of the cloisters. Stones dripped centuries of black slime; his footsteps echoed under the arches.

I ran after him and grabbed him by the arm. 'What exactly was Harry's answer?'

'He swore he hadn't screwed Lily,' Jayden said as he broke free. 'He shouldn't have talked about her that way, like she was nothing, just a piece of meat. That's the reason I hit him.'

And kicked and punched him, smashed his fists into his face, his feet into his ribs. I could definitely relate to why Jayden had done that.

'Come!' he told Bolt.

The gleaming-eyed dog was at his heels in an instant. They walked away from the ruins along the dead riverbank, stick man and stick dog.

I went back to school, found Jack in the sports centre and told him every detail of my conversation with Jayden.

Whenever I paused for breath, he repeated the same two small words 'A tooth?'

'It's so weird,' I sighed. 'I mean why?'

'Does a psychopath have to have a reason?' Jack wondered.

'No, you're right.' But the idea scared me. If there was no logic attached to the action, how could the police or Jack or me or anyone sane follow the clues? Holding Jack's hand across the table in the mezzanine coffee shop, I felt we were Hansel and Gretel scattering crumbs in the forest, using it as a trail to follow to get back home, only to find that birds had come along and eaten every last one.

Children lost in the forest that was me and Jack.

Then, during a free double period next day, after I'd watched the morning headlines on TV New Tragedy Strikes at Top Public School/Olympic Hopeful in Hospital Intensive Care I pulled myself together and decided to slide Lily's diary from its hiding place under Paige's mattress and take it to the old library where I could find a quiet corner to reread it among the newspapers and magazines.

I handled the diary carefully, stroking its dog-eared pale blue cover before I opened it at random.

February 14th Sent you-know-who a Valentine's card. Didn't get one back. Got one from Tom W and one from H. A not doing well so they changed her tablets.

I read between the lines, worked out that she'd sent Jayden a Valentine's card and received one from Tom Walsingham (the only Tom W I'd heard of around here) and one from Harry maybe. She wasn't interested in either. 'A' was her mum, I guessed, taking anti-depressants that didn't suit her.

April 1st P swears L is R-Patz lookalike hah! I say J is more movie/rock-star material than L think Joaquim Phoenix/Kurt Cobain. P played April Fool's joke on L apple-pie bed, extremely juvenile. He was not amused. Met J in Anslee shh!

Interpretation P is Paige and L is obviously Luke. Lily has hit on the stick man hieroglyph for Jayden, her secret, guilty passion.

On April 20th the stick dog made its debut, together with: Walked with J and B on Hereward Ridge.

May 24th Quiet time at J's house. Amazing.

Followed by the rectangle with four legs definitely a bed to mark the first time Lily and Jayden had sex, I was convinced. And I noticed it appeared often through the rest of May and all of June, with snippets of information about J's life his abusive father now living in a homeless hostel in Bristol, his love of football (Everton) and his dog. He found Bolt in an animal rescue centre and took him home without asking his mum. Bolt lived in the garden shed for three months until Jayden's mum relented and finally allowed him into the house.

July 2nd Met J after school. LOVE HIM!!!

And just so there was no room for doubt July 4th Met J after school LOVE HIM!!! Then the row of red hearts linked by the letters of Jayden's name and Am thinking of getting tattoo around ankle, etcetera.

The same entry had the reference to Lily's phone call with her mum, when the tyrant broke off their conversation which made more sense now that I knew how sick Anna actually was. I envisaged how worried Lily must have been about her mum and how Robert Earle had done his usual thing of ranting and dishing out orders for what he might have thought were good reasons (to protect Lily, Anna or both), but which turned out to be lousy psychology because it ended up with Lily permanently hating him and Anna in a psychiatric hospital.

I flicked forward to September 5th when the circle and dot drawing appeared for the first time the date Lily wanted to be the day of conception, but with a question mark and written some time after the event in a different coloured ink. Then back to late August, where I read and reread each entry.

August 22nd P's house. J texted me twelve times!!!

August 23rd P's house. Right now P hates L and loves Mistral. God, I despise horses stupid, smelly crap machines!!! Only 5 texts from J today MISS HIM!!! G and H arrived The day just got ten times worse.

August 24th no entry. August 25th no entry. How weird was that? I flicked back and forth through the diary and discovered that in the whole year she'd only missed one other day, right up until the day she disappeared. Yeah, that was definitely right a gap on March 14th, which was marked The T's birthday blank page and now again for the two days when Guy Simons and Harry Embsay had stayed at Paige's house to watch her compete at Burghley. The two blank spaces told me absolutely nothing, or maybe everything, I needed to know.

A chime from the carriage clock on the mantelpiece of the gothic fireplace made me realize that I'd stayed in the old library longer than I'd planned, so I closed Lily's diary and slipped it into the front pocket of my bag, ready to sprint across the quad for my French conversation class with Justine. 'J'ai un probleme, mademoiselle un grand mystere. C'est Lily le vingt-quatre d'aout, the vingt-cinq d'aout, elle n'a pas ecrit son journal!'

I was heading for the door when I came across D'Arblay speaking with Adam Earle in the European History section, a side annexe to the main building, where they obviously thought no one would interrupt them. I heard them just in time to backtrack and stay close without being seen.

'Yes, the new information in the pathologist's second report raises more questions than it answers,' D'Arblay was agreeing with what Adam had just said. 'I appreciate how difficult it must be for you and your parents.'

'Very frustrating,' Adam said. 'One part of me still says that this is a small, unexplained detail in an otherwise clear-cut case of suicide. But then of course I do understand that Inspector Cole has to investigate all possibilities.'

D'Arblay agreed again. 'The police have asked the hospital pathology department to double check their autopsy procedure, just in case there has been room for error.'

'An irregularity?' Adam surmised. 'Something procedural that might account for the missing tooth.'

'Exactly. In any case, Adam, please accept my deepest sympathy for the delay.'

'The family needs closure my mother especially.'

'How is your mother?' D'Arblay made another cheesy attempt at deepest sympathy.

Adam didn't reply so I had to imagine a shrug or a shake of his head before he moved quickly on. 'The real reason I'm here, D'Arblay, is to offer you some reassurance over the question of funding for the school.'

'Ah yes.' The bursar was back in brisk business mode where he was totally at ease. 'That was an unfortunate incident. While we understand the personal pressure on your father at the present time, we still felt it wise to ask our lawyers to address the legal situation in other words to study the original agreement between Robert Earle and the St Jude's Foundation. Of course the withdrawal of his generous donation would do great damage and we're hoping that in the cool light of day your father will reconsider.'

'That's why I'm here,' Adam assured him. 'To calm troubled waters.'

'Good, good,' D'Arblay murmured.

'I've looked into it myself and as a matter of fact there is no legally binding contract between my father and the school, but in spite of that I hope to persuade him that the obligation is a moral one.'

'Very good.' D'Arblay sounded less confident now that the media mogul's donation depended on his discovery of a sense of honour.

'Lily did well here at St Jude's,' Adam explained. 'I would say she even thrived.'

'Thank you, Adam.'

'She developed her artistic talents and she made good friends.'

'We all miss her.' (Cheesy again.) It was so fake it made me want to puke all over the section of shelves containing books about the French Revolution. We do we miss her! We feel it in our battered, bruised hearts. We don't just say the words!

'If only she could have kept her personal life on track,' Adam sighed, 'this terrible tragedy might never have happened.'

I pictured a nod, a sigh then back to business. 'So I can inform the principal that you'll work to secure the original agreement?'

'Tell him that I'll do my best.'

There was some handshaking and more murmuring before the two men emerged from the annexe and headed for the door. I stayed hidden until they'd left.

What now? I was already late for my French lesson 'Je suis en retard. Je suis desole, Mademoiselle Renoir' and I felt one of my sudden urges to talk to Adam Earle, the person behind the suit. I watched from a library window as he exchanged a final handshake with the bursar and walked slowly towards his car. Reckoning I still had time to intercept him, I left the library by a side door and sprinted towards the car park.

Adam was opening his car door as I slipped into the passenger seat.

'Alyssa!' he said in a way that suggested he expected trouble, but was ready to deal with it.

'Do you mind?' I said hurriedly, one eye on the journos at the gate. 'I thought we could talk.'

'Here?'

'No, while you're driving, if that's OK.'

He nodded and didn't say anything as I slid out of my seat and curled up on the floor. 'Why the cloak and dagger?' he asked once we were clear of the journalists and I was sitting normally again.

'I don't want to attract attention it might not be good for my health.' I explained about the Toyota incident and the attack on Paige's horse.

Even Adam couldn't conceal his surprise. 'You say you're being threatened, intimidated for what reason?'

'Maybe because they think we know too much.'

'"They"?'

'Whoever killed Lily.'

'If Lily was in fact murdered!' Adam's guard was up again as he drove along the familiar lane. 'I take it the police are following it up?'

'Yeah, they're trying to trace the guy who stole the Toyota and the kid with the Stanley knife, who it turns out is the same person.'

He reacted again not in a big way, just by raising his eyebrows a notch. 'You're sure about that?'

'Yeah, I saw them both. His role is to scare us and he's definitely doing a good job.' Too good a job, with my roommate in intensive care. 'I don't think the plan involved actually hurting Paige that was just the way it worked out.'

Adam stared at the narrow road ahead, evidently trying to block any normal, sympathetic response to the surprise news. His car tyres swished through deep puddles, throwing spray at the windscreen. 'This Toyota/knife guy you're saying he's scared you might have a vital clue that could lead to my sister's killer?'

'I guess.'

'And do you?'

I paused for a long time, watching the windscreen wipers' metronome motion and wondering how far I could trust Lily's big bro. 'Paige and I were there the day Lily died, right up until she packed her bag and left,' I said in the end. 'Five days later we watched them pull her body from the lake. We've gone over and over it in our minds.'

'So if anyone can work out what happened it would be you and Paige?'

'But right now just me.' I thought again of Paige in the ICU, pictured the beeping, erratic graph of her heartbeat.

'You shouldn't be here,' Adam decided.

'In the car with you?'

'No here at St Jude's. You should be at home while the police sort everything out.'

'That's exactly what Dr Webb said, and the bursar. They both put pressure on me, but I refused to leave.'

Stopping at a T-junction, Adam turned left on to a long, straight Roman road running parallel to Hereward Ridge. 'I appreciate your loyalty and determination on Lily's behalf, Alyssa. But I agree with '

'No,' I insisted. 'Lily would've done the same for me or Paige if.'