Caroline took out her phone and tried to ring Josh—just in case something happened to Teddy and he needed to get in touch with her. But it seemed that she could not call America on her mobile. Feeling frustrated, she rang her grandmother. “All well so far,” she said, giving her details of the pensione where she would be staying. “Would you mind telephoning Josh for me and letting him know I have arrived safely and he can call me at the hotel number? And give my love to Teddy, and tell him I’ll see him soon . . .” Her voice trailed away, and she blinked back tears.

As darkness fell, she asked the woman at the reception desk for advice on restaurants.

“You like to eat fish?” the woman said.

Caroline nodded.

“Then you come out and follow the canal to the other side of Dorsoduro. It is called the Zattere. Good fish restaurants on the waterfront there. Don’t eat near St Mark’s or Rialto. All tourist places.”

Caroline thanked her and set off, following the narrow canal until it opened on to a broad waterway on which lights sparkled. There was obviously outdoor seating in summer, but on this chilly evening she went inside the first restaurant she came to. There were only two couples at other tables, and she was greeted warmly. There she ordered an antipasto of tomato and mozzarella and followed it with spaghetti with clam sauce. A split of Prosecco washed it down well, and she walked back, hearing her footsteps echoing from across the canal.

Back at the pensione, she ordered a coffee, and the proprietress sat beside her after she served it. “You come alone to Venice, on business?” she asked.

“No. A personal mission,” Caroline answered. “My great-aunt just died. I am bringing her ashes to a place she loved.”

“Ah.” The woman smiled. “You care about famiglia . That is important.”

“Are you from Venice?” Caroline asked.

“Of course. I was born here,” she answered.

“Do you remember a pensione called Regina?”

The woman frowned. “The name sounds familiar, but no. I don’t think I ever knew of such a pensione. Certainly not now.”

Emboldened, Caroline went to her room and returned with the box. “My aunt also left me these. Do you have any idea what they might be?”

She tipped out the three keys and held them in her hand. The woman took them, one at a time, turning them over in her hand. “This big key could open any door in this city, I think. Every house has keys like this.” She took the brass key with the winged lion on it. “This one has the symbol of our city. St Mark, yes? It could be a key for a special occasion? A festival maybe? I have not seen one like it, but you will find the lion of St Mark everywhere. On souvenirs, made in China, eh?” And she laughed.

Caroline took them back. It seemed hopeless. In her room she turned the keys over in her own hand. What did Aunt Lettie want her to do with them? Find out which door the big key would fit, when it might belong to any house in the city? Did it actually come from Venice? Why would Aunt Lettie have needed to open any door apart from the pensione where she stayed? And why was Venice so special to her?