"We have to call the police," Natalia said.

"And what are you going to tell them?"

"That there was a car with naked women sitting inside."

I called Ralf's cellphone number. I got his voice mail. I tried again, until we realised that there was a ring coming from his shoulder bag, which he had stored behind the counter. In it were — in addition to two oranges — his wallet and his guidebook. We waited for the carabinieri above the shop in a room painted green. All we could do was provide them with Ralf's description — that, and what he had shouted. N. said that it was evidently one or several of the prostitutes he had made friends with last summer, at the beach south of Ostia. Had he been a client, the carabinieri asked? "Probably," she said.

The short carabiniere was poker-faced, the tall one stared at me as if I were the offender. They took down Ralf's cellphone number. Natalia reviewed Ralf's recent calls, but it looked as if he had made none since 6 December, the date he arrived in Italy. He had received only a few SMS messages from Vodafone, promising "low-rate travel calls". I didn't find any Italian area codes in his stored numbers — except for ours. Towards the end, I gave the police our
address at the Villa Massimo and was given a number to call as soon as Ralf got in touch with us again.

When Raimondo offered to cancel our visit to the aquarium, we both rejected the idea simultaneously. Nothing in the world seemed more worth the effort than to head off to the aquarium with Natalia and the girls. At that moment, I probably would have welcomed most any other suggestion. I just wanted to get away from the spot where Ralf had shouted, "Stop!" and "Felice!"

During the short taxi ride, I caught myself constantly staring into other cars. But why would pimps want to smuggle naked women through the city in broad daylight? The carabinieri had asked no questions along those lines, whatever that meant. We had to drive back through the long tunnel, since the Stazione Zoologica Anton Dohrn — its official name — lies on the far side of the mountain, in a little park.

There was an unpleasant fishy odour at the ticket counter. But that didn't bother me. On the contrary, anything that put distance between Ralf and us made me happy.

Christiane Groeben, the Stazione's archivist, who has lived in Naples for more than 30 years, led us upstairs to the hall with the frescos by Hans von Marées. For the girls, the attraction was the fish, but we wanted to give the frescos a look. I tried as best I could to concentrate on her comments.