Even though he had suspected Waaler for a long time, it came as a shock to receive confirmation. Not least because it meant that there had to be more moles working with him in the department. Prince could not have operated with such a wide network as he had done without help. That in turn meant that Harry could not trust anyone. So he kept his mouth shut about what Roy Kvinsvik had told him because he knew he would only get one chance, and the whole sordid truth would have to come out in one go. And he would have to be absolutely sure that the root came with it; if it didn’t he was done for.

That was why Harry had secretly begun to work on assembling a watertight case against Waaler. However, since he didn’t know who it was safe to talk to, this turned out to be more difficult than he had imagined. He began to trawl through the archives after the others had gone home for the day, to tap into the internal computer network, to print out e-mails and lists of incoming and outgoing telephone calls from people he knew Waaler associated with. In the afternoons he sat in a car near Youngstorget and kept an eye on Herbert’s Pizza. Harry’s theory was that the neo-Nazis frequenting the pizzeria were also smuggling arms. When this theory did not produce any leads he began to shadow Waaler and a number of his colleagues. He concentrated on those he knew spent a lot of time with guns at the firing range in Okern. He followed them from a safe distance, sat outside their homes, shivering in his car while they slept indoors, and returned home to Rakel early in the morning, totally exhausted. He slept for a couple of hours and then went to work again. After a while she asked him to sleep in his own flat on the nights when he had double shifts. He hadn’t told her that his night work was off the record, off the time sheets, off the awareness of his superiors, off almost everything.

Then he started doing a turn off Broadway too.

First of all, he dropped by Herbert’s Pizza one evening, then another, chatting with the guys, buying rounds of beer. Of course they knew who he was, but free beer was free beer and they drank it, grinned and kept their mouths shut. He gradually realised that they didn’t know anything, but he still continued to go there, he wasn’t quite sure why, perhaps because it gave him the feeling that he was close to something, the dragon’s lair. All he had to do was be patient, he only had to wait and the dragon would emerge. But neither Waaler nor any of his acquaintances ever turned up. So he went back to watching the block where Waaler lived.

One night, at 20 degrees below freezing point, the streets completely deserted, a man wearing a short, thin jacket came walking towards his car with the rolling gait that characterises junkies. He stopped outside the entrance leading to Waaler’s block, looked right then left and attacked the lock with a crowbar. Harry sat and watched, fully aware that he risked being exposed if he intervened. The man was presumably too stoned to attach the crowbar properly and as he yanked it down, a large chunk of wood detached itself from the door with a splintering sound. As he did it, he fell backwards and landed in a pile of snow at the front of the block. And that was where he stayed. Lights came on in a couple of windows. The curtains in Waaler’s flat moved. Harry waited. Nothing happened. Twenty degrees below zero. The light was still on in Waaler’s window. The junkie didn’t stir. Afterwards, Harry often wondered what the hell he should have done. The battery on his mobile had gone flat because of the cold, so he couldn’t have rung casualty. He waited. The minutes ticked by. Bloody junkie. Twenty-one below. Sodding junkie. Of course he could have driven away, gone to casualty and told them about him. Something moved by the entrance. It was Waaler. He looked comical in dressing gown, boots, cap and mittens. He was carrying two woollen blankets. Harry could not believe his eyes as Waaler checked the junkie’s pulse and pupils before wrapping him in the blankets. Waaler just stood there flapping his arms around to keep himself warm and peering in the direction of Harry’s car. A few minutes later the ambulance rolled up in front of the block of flats.

That night Harry went home, sat down in his wing chair, lit a cigarette and listened to the Raga Rockers and Duke Ellington. Then he went to work, although he had not been out of his clothes for 48 hours.

Rakel and Harry had their first row one evening in April. He had cancelled a weekend trip at the last moment, and she pointed out that this was the third time he had broken a promise within a very short space of time. A promise to Oleg, she said. He accused her of using Oleg as an excuse and that what she really wanted was for him to prioritise her needs over finding the person who had taken Ellen’s life. She said Ellen was a ghost, that he had shut himself up with a corpse, that it wasn’t normal, that he was feeding on the tragedy, that it was necrophilia, that it wasn’t Ellen who was driving him but his own lust for vengeance.

‘You’ve been hurt,’ she said. ‘And you’ve let everything else go so that you can get your revenge.’

As Harry fumed out of the house he caught a glimpse of Oleg’s pyjamas and red eyes behind the stair rails.

After that he stopped doing anything that did not have a direct connection with his pursuit of those guilty of Ellen’s murder. He read e-mails under the low light of table lamps, stared at the dark windows of detached houses and blocks of flats waiting for people who never came out, and snatched a few hours’ sleep in his flat in Sofies gate.

The days grew longer and lighter, but he had made absolutely no progress. One night, out of the blue, a nightmare from his childhood returned: Sis, her long hair trapped, the expression of horror on her face. He was rigid with fear. It returned the following night. And the night after.

Oystein Eikeland, a childhood friend who drank at Malik’s when he wasn’t driving his taxi, told Harry that he looked shattered and offered him some cheap speed. Harry refused. Exhausted and angry, he continued with the relentless search.

It was just a question of time before it all unravelled. Something as prosaic as an unpaid bill was all it took to trigger it. It was the end of May and he hadn’t spoken to Rakel for several days. He was woken in his office chair by the phone ringing. Rakel said that the travel company had reminded her that they hadn’t paid for the farm in Normandy. They had a week’s grace, after that the travel company would rent the farm out to someone else.

‘Friday is the deadline,’ were Rakel’s last words before ringing off.

Harry went to the lavatory, splashed some cold water over his face and confronted his reflection in the mirror. Beneath his wet, closely cropped fair hair he saw a pair of bloodshot eyes with dark bags under them and drawn, hollow cheeks. He tried a smile. Yellowing teeth grinned back at him. He didn’t recognise himself. And he knew that Rakel was right, it was a deadline. For him and Ellen. For him and Tom Waaler.

The same day he went to his closest superior officer, Bjarne Moller, who was the only person at Police HQ he trusted 100 per cent. Moller had alternately nodded and shaken his head as Harry told him what he wanted. Fortunately, he had said, that was not his pigeon and Harry would have to take it up directly with the Chief Superintendent. Nevertheless, he thought that Harry should think twice before he went to see him. Harry went straight from Moller’s square office to the oval office of the head of Kripos. He knocked, went in and presented what he had to say, about the witness who had seen Tom Waaler together with Sverre Olsen, and the fact that it was none other than Tom Waaler who had shot Olsen while arresting him. That was it. That was all he had after five months’ slog, five months’ shadowing, five months on the verge of madness.