"I know what that means! It's a Greek word. Palin means 'back' and drome means 'runs', so it's a word that runs the same way backwards as it does forwards."

"And there are other ways you can play with it," said Tertius. He looked at Flavia thoughtfully. "You're a very bright girl."

"So are you," said Flavia, and then giggled. "Not a bright girl. But you do know a lot for a baker's slave."

Tertius nodded sadly. "I used to be a schoolteacher," he sighed. "Before I fell into debt and had to sell myself into slavery."

"Did you ever teach Pistor's sons?" asked Flavia.

"No," said Tertius. "Though I'd like to. Pelops and Erysichthon are bright boys."

"Who?"

"Oh, those are just my private nicknames for Porcius and Ericius. No," sighed Tertius. "I was never a private tutor. Before they let me go, I used to be schoolmaster at the Forum School."

I'M GLAD I DON'T GO TO THE FORUM SCHOOL, wrote Lupus on his wax tablet.

"Why not?" asked Flavia, taking a cube of white goats' cheese. It was noon and they were having a light lunch back at her house.

Lupus took his brass stylus in his right hand and pretended to bring it down hard on the knuckles of his left. "They beat you?" asked Jonathan.

Lupus nodded. Then he twisted his own ear and grimaced. "And they twist your ear?" asked Flavia.

Lupus nodded again and wrote on his tablet: THEY RECITE EVERYTHING.

SO BORING he added.

"Yes," said Flavia glancing at Lupus's tablet. "That's how most children in Italia are taught. We're lucky to have our own tutor."

"Especially one being as nice as Aristo," said Nubia. "And did Porcius or Ericius pull any bread rolls out of their satchels?" asked Flavia. "Maybe to sell them to their classmates? Or bribe the master not to beat them?" Lupus shook his head and wrote on the tablet: NO ROLLS.

"So that probably rules out those two," murmured Flavia. "What about you, Nubia? Did Titia notice that you were following her?"

"No," said Nubia. "I and Caudex are very hidden. We follow her to market and then to temple of Venus. Caudex waits outside and I pull palla over my head and go in her behind."

"You mean you went in behind her," Jonathan laughed. "Yes. Titia gives the lady priest a gift and puts a clay thing on the shrine."

"What clay thing?"

"After Titia leaves I go and quickly look. Behold! It is little clay eyes."

"Oh," said Flavia. "You mean a model of eyes, made of clay?"

Nubia nodded.

"That will be a votive," said Flavia. "A votive is a model of the part of your body you want cured. It reminds the goddess of your prayer."

"Is there something wrong with somebody's eyes?" said Alma, coming into the dining room. She set a platter of bread drizzled with olive oil on the table.

They all reached for a piece and Flavia nodded. "Titia. She has cross eyes and wants to be beautiful to win a husband."

"Oh yes, Titia. The poor thing," said Alma. "Pomegranate juice or barley water?"

"Pomegranate juice, please." As Alma went out Flavia turned back to Nubia. "You said Titia gave the priestess a gift. What was it?"

"I am not certain," said Nubia. "But I think it was small loaf of bread."

They all looked at one another. "A loaf?" asked Flavia. "Not a roll?"

"No," said Nubia. "It was being a loaf."

"What about you, Jonathan? You followed Teneme. Did he run away again?"

"No." Jonathan sighed and spat an olive stone onto his plate. "Teneme just went to the Imperial Granary and stood in a queue and collected a big bag of grain. Then he brought it back to the bakery. He arrived just as you left, Flavia. I saw you and Scuto walking home. Did you find out anything?"

"Not really. I talked to the slave called Tertius. He does the accounts. I found out that Pistor doesn't trust him and has started to check his calculations. But there was one thing . . . I just remembered. It might be a clue."

"What?"

"Tertius is very educated. In fact, he used to be a teacher at the Forum School. He collects puzzles and codes like me, and he's given Porcius and Ericius private nicknames. He calls Porcius Pelops, which makes sense."

"Why?" asked Jonathan. "Who is Pelops?"

"He was an ancient Greek who loved racing chariots," said Flavia. "And we know Porcius is mad for the races so that fits. But Tertius called Ericius something else. Eris--something." She chewed an olive thoughtfully. "Erysichthon. That's it! Now if only I could remember where I saw that name . . ."

Alma came into the dining room with four beakers on a tray.

"You know," said Jonathan, "There are still two people we haven't followed."

Flavia nodded. "Pistor's wife Fausta," she said, "and her slave-girl."

"Oh, my dears, you don't want to follow Fausta," said Alma, setting down the tray and handing out the beakers. "Why not?" said Flavia, taking a sip of pomegranate juice. "She's far too preoccupied to steal a dozen bread rolls once a week," said Alma, and then lowered her voice to a scandalized whisper. "It's common knowledge that she and her slave-girl go down to the Forum Baths every afternoon to watch the gladiators work out!"

Flavia stood on tiptoe on her father's table and stretched for the highest shelf.

Nubia looked round nervously. "Flavia. You are not supposed to be reading the Ovid."

"I know," said Flavia, "but I just have to look up. one thing. Are you keeping a lookout, boys?"

Jonathan and Lupus each stood in the doorway of the study. Lupus grunted yes.

"Pater or Alma might come home any minute so I need to be quick. If I can just . . . Oh, Pollux!"

A cylindrical leather scroll case tumbled from the top shelf. Nubia caught it deftly in both hands. Then she sneezed; the scroll case was dusty.

"Well caught, Nubia!" Flavia clambered down off the desk. She glanced towards the folding door of the study. "Any sign of Caudex?" she whispered.

"He's in his cubicle," said Jonathan. "I think I can hear him snoring."

Flavia nodded with satisfaction, turned back to the scroll case and lifted off the lid. "Ten. I think it's in scroll ten." Her finger hovered over the open case for a moment and then she pulled out a scroll.

"Ten!" she said, and unrolled it on her father's desk. Nubia watched Flavia expertly twist her hands so that the blocks of writing scrolled past her eyes.

Flavia murmured as she read. "Ugh!" she shuddered as she read one passage.

At last Flavia whispered: "Eureka! Here it is: right at the end. I knew it was in Ovid." She glanced around at her friends. "A king named Erysichthon scorned the gods something you must never do, by the way - and he cut down a sacred tree. He also killed the nymph who lived there, so the goddess Ceres cursed him with a terrible hunger. Listen: 'a desperate craving for food rules his ravenous jaws and his churning stomach . . "

Flavia's finger moved down the scroll: "And here: 'His hunger remained untouched and his greed unsatisfied' Flavia shuddered. "Finally he gets so hungry he devours himself," she said.

Nubia stared at Flavia in horror. "That is a story of Ovid?"

Flavia nodded as she rolled up the scroll and dropped it back into its cylindrical case.

"I'll bet Tertius calls Ericius 'Erysichthon' because he's always hungry." She climbed back up onto the table and replaced the scroll case on the highest shelf.

"Jonathan," she said thoughtfully, as she jumped down off the table again.

"Yes?"

"Do you think your father would mind if I asked him a medical question?"

"Worms," said Mordecai ben Ezra. "Roundworms, tapeworms, whipworms. They are all types of parasites that can make a man ravenously hungry. Other symptoms include coughing, wheezing and vomiting."

"Yes!" cried Flavia. "Ericius coughed a lot. And he doesn't look very well."

"What is parasite?" asked Nubia.

"It's an animal that lives off another animal to survive," said Mordecai.

The girls looked at one another and shuddered.

"Ugh," said Flavia. "I could never be a doctor."

"Why not?" Mordecai smiled at her from beneath his dark turban. "Being a doctor is a lot like being a detective. You have to discover the underlying causes for things that happen."

"I think I have worms," said Jonathan slowly. "I wheeze."

"That's because you have asthma," said Mordecai. "I'm fairly certain you don't have worms."

"But I'm hungry all the time."

"And that's because you're an eleven-year-old boy. Your body is growing faster now than at almost any time in your life. It needs bread to live."

"But how can I tell whether I have worms?"

"Do you really want to know?"

They all nodded.

"After you've been to the latrine, you must take the bucket into bright sunlight and carefully examine your stool." "My stool?" Jonathan looked puzzled. After a moment understanding dawned in his eyes: "My stool! Ugh!" Lupus guffawed.

"Yes," said Jonathan's father. "And if you see anything . . . er . . . moving there, well, you probably do have worms."

Flavia looked at Mordecai. "So if I wanted to find out whether Ericius has worms, then I'd have to . . ."

Mordecai nodded. "You'd have to take his latrine bucket and have a good look."

Flavia looked ruefully at her three friends. "I guess," she said, "a detective does have to empty latrine buckets after all."

"Yes," said Mordecai, coming into the atrium a few hours later. "I've just been round to Pistor's. I'm afraid young Ericius does have worms. I've prescribed a tincture of pomegranate skins and wormwood, after a three day purge. Poor boy."

"I guess you can't blame him for stealing the bread rolls," said Flavia. "I just hope his father doesn't beat him."

"Oh, he's not your culprit," said Mordecai. "I spoke to him gently and he swore he wasn't the thief."

"And you believed him?" said Jonathan.

"Yes. The poor boy lives in fear of his father." "Pollux!" muttered Flavia. "If Ericius didn't steal the bread rolls then who in Hades did?"

"Let me have your theories," said Flavia, absently scratching a flea-bite on her forearm. "And remember to give me the motive, means and method. That's what Pliny says in his scroll." They were sitting in the boys' bedroom, the girls on Jonathan's bed, the boys on Lupus's.

Jonathan cleared his throat. "My theory is that Porcius is stealing the bread rolls," he said. "His motive could be to raise enough money so that he can run away to chariot school in Rome. His father obviously wants him to become a baker, not a charioteer."

"That's an excellent motive," said Flavia. "And we know he has the means; he works at the shop front every morning. But what about his method?"

"I'm not sure," said Jonathan. "Maybe he slips some rolls into his satchel and then sells them to the other boys in his class."

"But remember, it was always a dozen rolls and it's only every seven days."

Jonathan sighed. "I know. That's what I can't figure out."

"Nubia," said Flavia. "Who do you think stole the bread?"

"I think Titia is stealing the bread to give to the lady priest at the temple of Venus. If Titia is giving the lady priest much bread then the god Venus will be favourable to her prayers and make Titia's eyes not crossed any more so she can marry a handsome man."

"Good reasoning," said Flavia. "But again: why every seven days and why a dozen?"

Suddenly Lupus gave a grunt of excitement. I KNOW WHY XII, he wrote on his tablet. They all leaned forward eagerly as he wrote: EACH TRAY FOR ROLLS HOLDS XII "Brilliant!" cried Flavia. "Someone could grab a tray and take it. But why just one tray?"

"It's quick!" said Jonathan. "You grab the tray, empty it into a sack or satchel, then put it back."

"And maybe the person's bag holds just about twelve rolls," continued Flavia. She sighed. "That doesn't really help us. Titia could put twelve rolls in her shopping basket but the boys' school satchels could hold about a dozen rolls, too."

Lupus wrote on his tablet: I THINK TENEME DID IT "Motive, means and method," said Flavia briskly. "What motive would he have; why would he steal bread rolls?" SUPPLIES FOR IF HE RUNS AWAY?

"That's worth considering. But remember, the thefts have been occurring for half a year. If he's been storing up supplies for when he runs away . . . well, some of those rolls will be pretty stale." Flavia sucked a strand of hair which had come unpinned. "And we still come back to that strange clue: why every seven days? I'm certain that's the key to this mystery."

"Tomorrow," said Flavia, "I'd like to post watch on Pistor's bakery again. We'll have to do it before lessons, so we'll need to be up very early." Flavia tore a piece from the last of the special plaited Sabbath loaf. She and Nubia had been invited to eat dinner at Jonathan's and now the four friends were dining with his sister Miriam and his father Mordecai. The six of them sat on floor cushions around a low hexagonal table.