‘What’s your view, Captain Golightly?’ asked Peter.

‘I suspect that the same man is responsible for all four deaths.’

‘And they’ve come in fairly close succession.’

‘It’s almost as if the killer is out of control.’

‘Oh, I think he’s very much in control, Captain,’ said Paul. ‘He’s systematic and deadly. There’s only one thing we need to ask.’

‘And what’s that?’

‘Who is his next target?’

Getting inside the house was more difficult than he’d hoped. His first problem came with four legs attached. A servant brought a dog into the garden to relieve itself and the intruder had to dive into the bushes to hide. The animal then scampered around the lawn, barking aloud. When it came towards him sniffing the grass, the assassin reached for his dagger so that he could parry it away but it was a false alarm. It got within yards of him. The servant whistled and the dog trotted obediently back to him. Wet and cramped, the man in the bushes had had a narrow escape.

He could now tackle the second problem. After he’d established that the study was not at the rear of the house, he realised that he’d have to enter it at the front. Even though the weather kept most people away, a passer-by might notice someone trying to climb in through a window. It was a chance that had to be taken. He consoled himself with the fact that – safely back inside the house – the dog wouldn’t be able to attack him. He simply needed to work fast. Creeping to the front, he was able to pick out the study at once because it was the only room in which there was no light. He first looked up and down to make sure that nobody was about, then he took out his dagger again and attacked the window. A minute later, he was inside the house.

As he’d suspected, the door of the study was already locked. Groping his way in the darkness, he reinforced his security by jamming a chair under the knob. It made him feel confident enough to light an oil lamp so that he could take stock of his surroundings. Though it was relatively small, it was exquisitely designed. Oak bookshelves lined two walls and were packed with volumes in identical binding. Over the mantelpiece there was a portrait of a dignified old man in the uniform of a major. He bore a clear resemblance to the person the assassin had murdered in St James’s Park. The desk was close enough to the window to profit from any daylight. Predictably, it was locked.