Bravo wrote the nonsense words onto a scrap of paper. On the line below, he wrote a simple equation: 54-42=8.

"There are fifty-four ridges on the edge of this coin," he told her. "There are, as you know, twenty-one letters in the ancient Latin alphabet. Double that, you get forty-two." He pointed to the first letter of the phrase. "My father started out using the code Caesar devised, moving each letter of the original message by four to encrypt it, so alpha becomes delta and so on."

"That's a pretty easy code to break," she said.

He nodded. "That's where the equation comes in. Only the first letter is substituted this way. From then on, eight is the key."

"So the second letter is substituted for the eighth letter in the alphabet."

"Yes, and then we work forward. The third letter of the text uses nine, the fourth letter ten, until we reach twenty-one. Then we go back to eight, and so on."

"So what did your father write?"

Bravo finished up the decoding, then showed her the result.

"In alms cabinet purse." She shook her head. "Do you know what that means?"

"I think we'll have to go to I Mendicoli to find out." He paid the bill and they left the cafe.

With the rising of the sun, dawn had dissolved into a morning already hot and wet. By now the children were at school and the college-age art students on their way to classes in astonishing medieval buildings, sketchpads tucked neatly under their arms as they jabbered away on cell phones.

"God, it stinks," Jenny said as they passed over a canal.

Bravo laughed. "Ah, yes, the stench of Venice is an acquired taste."

"Count me out."

"Given time, you'll change your mind, I guarantee," he said.

Several times Jenny slowed, looking around as if unsure how to proceed, even though it was Bravo who was leading the way.

"What's the matter, don't you trust me?" he said. "You look like you're lost."

"I have a feeling we're being followed. Normally, I'd be able to check reflections in shop windows or in cars' side mirrors, but here that's impossible. At this hour there are few shops and, of course, there are no cars. I've been trying to use the canals, but because it's in motion water is a notoriously unreliable reflective surface."

They moved on, in the midst of a shroud of anxiety. Smells came to them of fermentation-the lees of wine-the whiff of an unseen woman's perfume, the distinct scent of the pale Istrian stone, borne aloft as if on St. Michel's gauzy wings against the deep-green water, from which emanated the ever-present rankness of decay. Even in brightest day, there was about Venice an acute sense of mystery. One was always turning a corner, hearing footfalls approaching or retreating, coming from narrow alleys into ancient campi in which could be seen clumps of elderly men speaking in hushed tones or a dark figure, furtively exiting the square.

Their first stop was in San Polo, where the Rialto Bridge spanned the Grand Canal just as it has since 1172, when the first boat bridge was built. Up until the nineteenth century the Rialto was the only link between the two sides of the city. As they crossed, shops on either side of the bridge were opening, their doors thrown wide and tourist-friendly signs put in windows and beside doorways.

The Banco Veneziana was just past the Erberia, an outdoor market that dated back to the time of Casanova. Here were sold herbs and all manner of produce brought in each morning from the small out islands that dotted the lagoon. The bright spicy scents of green herbs mingled with the heady odors of blood oranges, castradure (baby artichokes) and spareselle (pencil-thin asparagus), as well as perfumed sprays of fresh flowers. As they worked their way through the happily chattering crowds, Jenny, clearly uncomfortable, kept an eye out for tails, which was made more difficult amid the dense bustle of the wholesalers, packing up to make room for the arriving retailers.

The bank was in an arcaded building of the Venetian-Byzantine style-the front was a mass of slender arched and columned windows-that had been rebuilt following the great fire of 1514 that had devastated it as it swept through the city. Like many buildings in Venice, the architecture was full of ornamental filigrees, intricately carved stone statues and stylized Gothic cornerstones. Inside, marble walls rose up to a domed ceiling into which had been set a marvelous mosaic of Venetian ships at full sail.

Behind the high banquette, they found a slim, middle-aged gentleman. Bravo spoke to him for a moment, and he handed over a form on which Bravo was required to write nothing more than the account number he had decoded from his father's dog-eared notebook, not even his name.

The banker took the form and disappeared for not more than three minutes. When he returned, he opened a section of the banquette. He allowed Bravo through, but not Jenny. He was polite and apologetic, but quite firm.

"I trust you understand, signorina," he said. "It is the policy of the bank to allow entrance only to the account holder. It is a question of possible coercion, you see."

"I understand completely, signore," she said with a smile. And to Bravo, "I'll be outside, looking for our friend." She meant Michael Berio, whom she suspected of following them.

Bravo nodded. "I won't be long."

The banker led him across the marble floor, up a staircase into a small hushed anteroom. Beyond was the massive open door to the safety deposit boxes. Of course, the vaults of Venetian banks would be upstairs, rather than downstairs, to protect against the periodic floods.

The banker left him in a small chamber-one of six that lined the left-hand side of the anteroom-and some moments later returned with a long gray metal box, which he put on the table in front of Bravo.

"I will be just outside, signore," he said. "You need only to call me when you are finished." He left without a backward glance.

Bravo sat staring at the box for a moment. In his mind's eye he saw his father seated where he himself now sat, the open box before him, filling it in his mathematically precise fashion. Bravo reached out, put his arms around the box, as if he could feel the last traces of his father. Then, with a convulsive gesture, he threw open the lid.

Jenny stood in the shadows beneath the bank's arcade, peering out at the glare. She leaned nonchalantly against one of the arches and made a good show of looking bored as she sipped a small cup of blood-orange juice she had purchased from a cart just opposite. She savored the sweet-tart taste but nothing else. As her eyes worked the people criss-crossing the campo, she felt a kind of depression weighing on her, as well as a dull headache, as if Dex's ghost were sitting on her head.

The deeper she got into this assignment, the worse she felt. She asked herself again why she had taken it, but the answer was as obvious as it was deflating: Dex had asked her to take it, and she never refused him anything. Hadn't he proved that he knew what was best for her? That had included, she'd assumed, this assignment guarding his son, but assumptions never took into consideration the curve balls reality threw at you. And Braverman Shaw had turned out to be one helluva curve ball. I can't let it go on like this. When am I going to tell him the truth? she asked herself. You have to let it go on like this, she answered herself. The moment you tell him, everything will blow up in your face and you'll have lost him.

"Have you spotted Berio?"

Jenny whirled, startled. "Um, no, but that doesn't mean he isn't here somewhere, spying on us."

"He only wants to protect us."

They began to walk toward the Dorsoduro, leaving the knots of people behind. Their footsteps echoed off the walls and narrow cobblestone streets, whose colors were made illusory by the reflections from the canals.