I walked to the other side of the bridge and only there did the roar of the water subside. That sudden change in volume shifted something in my brain. Maybe it was the image of that water, that sense that the real action of a bridge is not above it but below. All that water and talk about the keys had set something off. What happened to Salati, I realised, hadn’t happened upstairs, in the building, up top. It must have happened below.

I pulled out my phone and tried to get through to the pathology department. A sleepy voice came to the phone.

‘Garrone?’

‘Sì.’

‘My name’s Castagnetti. I’m working on a case and I believe you did the autopsy.’

‘I know you. You’re that private dick.’

I made a grunt. ‘You did an autopsy…’

‘I do dozens every day.’

‘Must be fun. The man’s name was Salati.’

‘The guy who used to have a shop on Via Cavour?’

‘Exactly.’

‘I zipped him up yesterday.’

‘And?’

‘The tidiest suicide I’ve ever seen.’

‘What do you mean?’

‘He was over ninety kilos, but his fall was so light he didn’t break a bone in his body.’

‘He didn’t jump?’

‘If he did, he flew down.’

‘So why’s everyone talking about suicide?’

‘Guesswork.’

‘So what killed him?’

‘Head injuries, sure, but not from falling to the ground. I would say it was something with a series of small, sharp protrusions… like an athlete’s spikes, or football boots with sharpened studs.’

‘You’re sure about this?’

‘There’s not much certainty about death but some things seem quite probable.’

‘Like it’s long.’

‘Yeah, right.’ The man laughed. ‘His skull and neck and back were perforated with these little indentations.’

‘How big?’

‘Fairly tiny. There were between eight and fifteen spikes for each blow. On the skin you can just see the outline of the shape holding those spikes. It’s slightly larger than a postage stamp. It wasn’t the spikes that killed him – they’re fairly shallow – it was the force behind them. It was some kind of hammer…’

‘You’ve got photographs of these wounds?’

‘Sure. Sent them up to Dall’Aglio yesterday.’

‘Time of death?’

‘We got the body yesterday morning. He had been dead roughly twelve hours. That puts the time between nine and eleven the evening before.’

I put the phone down. If Salati hadn’t fallen from his balcony, it meant that a woman could have been responsible. There might not have been a fight up there at all. It might have happened on the ground and he might have been hit from behind. Someone had tried to make it look like suicide, gone upstairs to open a window, tried to make it look like a jump. It was an amateur, that was for sure.

It wasn’t surprising that Dall’Aglio wasn’t publicising the news. He had enough media interest around him without them getting even more excitable. But it would come out sooner or later. The giallo would become a murder. It would go national by tonight.

My phone was vibrating.

‘Sì.’

‘Castagnetti?’ It was Dall’Aglio.

‘Why didn’t you tell me it wasn’t a jump? Salati died on the ground.’

‘You’ve spoken to Garrone?’

‘Sure. So much for swapping favours.’

‘I’ve told you before, I don’t trade favours. But I’ve got something for you. You’re going to like this. My women in the finance department have traced the Visa record for the Gazzetta payment.’

‘Go on.’

‘Unfortunately it’s not Riccardo. I half hoped we would hear that it was genuine, that it really was your boy. As it is, I really don’t understand it.’

‘Give me the name,’ I said impatiently.

‘Massimo Tonin, the lawyer.’

‘Tonin?’ I laughed.

‘What’s so funny?’

‘It’s not funny, so much as…’ I shook my head. Humans never cease to surprise me, but Tonin was certainly a weird one. ‘I got the impression he really cared for that boy.’

‘Maybe that’s why he paid to put a piece in the paper.’

‘You don’t believe that?’

‘I don’t know what to believe any more.’

‘I reached that point a long time ago.’ I couldn’t understand why old Tonin would want to pretend to be Riccardo in print. Unless he didn’t want people to think he was dead, unless he wanted people to think his boy was alive and well.

‘We’re going to bring him in,’ Dall’Aglio said.

I felt my limbs tense up. Once he was in custody he would be all buttoned up. I would have no element of surprise. I wanted to race round to his now, before they brought him in.

But I couldn’t do that. I couldn’t race round there on information Dall’Aglio had just given me. Dall’Aglio would accuse me of interference and favoreggiamento. I would have to come in on Dall’Aglio’s coat-tails.

‘I’ll come,’ I said.

Dall’Aglio didn’t say anything.

‘As an observer. Nothing else.’

Dall’Aglio was still silent. He must know, I thought, that this was my case as well as his. It was my information that gave him the breakthrough.

‘All right,’ said Dall’Aglio. ‘You know the rules. You don’t touch anything, you don’t say anything.’

‘Right. When’s the arrest?’

‘We’re going there now. Wait for us on Via Trento by the cinema.’

I put the phone down and went out. Tonin was a strange one. He had seemed to me one of those astute lawyers. He might sell his soul for a few percentage points, but I couldn’t see him knocking off his own son. But then, you never think that when you first set eyes on someone. There is no dark streak, not until you know someone’s killed another human being and you put that streak on them yourself. They’re just ordinary people who do something irreversible. They’re all different, and Tonin might be just one more specimen for me to study.

Dall’Aglio picked me up in the force’s luxury Alfa Romeo.

‘You armed?’ Dall’Aglio asked as soon as I opened the car door.

‘Sure.’

‘Give it to me.’

I reached inside my jacket and passed him the pistol. It wasn’t because Dall’Aglio didn’t trust me. He knew me well enough not to worry about me getting twitchy if it got tense. It was a power thing. It meant he was in complete control of the operation. I admired the formality, even though I didn’t like going after a suspect with only my bare fists.

Tonin came to the door before Dall’Aglio had even rung the bell. He stood there like a condemned man as Dall’Aglio read him his rights. Two officers then bundled him into the car. That was it.

‘I’m taking him to the station. You coming?’ Dall’Aglio said.

‘I’ll have a look round.’ I replied. There was no point going back to the station. We would hang around for at least two or three hours whilst they searched for evidence to lay on Tonin’s plate. I calculated that I might as well hang around and watch what happened at the house.

I went inside. The cadets were surprisingly efficient. Everything was turned upside down very neatly. I had expected them to send in the heavies, but it was all very deferential.

They went through all the drawers, pulled them out and looked underneath and behind. They took pictures off the walls, leafed through the books and magazines. The bathroom was pulled apart. They lifted up the shower tray and dismantled the bath. They listened to the plumbing and examined the surface of the soil in the garden. They went through the cypress and poplar trees with sticks. Still looking for those keys, I thought.

I wandered upstairs. It was a house like you used to see in American movies: a staircase wide enough for large plants where it turned a corner. The corridor upstairs was long and all lit up. Beings covered in white overalls kept coming out of rooms to the left and right.

I pushed into a room that looked like an old man’s place. There were suits in the wardrobe, a single toothbrush and razor in the bathroom. I took the top off a rectangular bottle of aftershave and sniffed it. It smelt like Tonin.