I was staggered. Even McGuffin had gone pale. But evidently Tim just hadn’t noticed there was anything wrong. The truth was he was so wrapped up in his own performance that he probably wouldn’t have noticed if his visitor had been hit then and there. I edged closer to the filing cabinet, ready to hurl myself behind it if any more bullets blasted into the room.

McGuffin slipped the gun into a shoulder holster and moved across the carpet, keeping clear of the window. “I need to use a phone,” he said. The words came out fast, urgent.

“Why?” Tim asked.

McGuffin hesitated. I think he still hadn’t figured Tim out. But then he had other things on his mind.

“You can tell me, Mr. McMuffin,” Tim went on. He tapped his nose. “I’m a private nose with an eye for trouble. Trouble is my middle name.”

McGuffin looked around the room. If he could have seen a telephone I reckon he would have used the cord to strangle Tim and then made his call uninterrupted. But whoever was waiting for him outside had him cornered. Time was running out. He had no choice. “Okay,” he said. “I’ll tell you.”

He sat down opposite Tim and took out a cigarette. “You got a light?” he asked.

Tim switched on his desk light. McGuffin scrunched his cigarette on the desktop. He seemed to have gotten a lot older in the last few minutes. “Listen,” he said. “I’m an agent. It doesn’t matter who I work for.”

“Who do you work for?” Tim asked.

“It doesn’t matter. I’m on the track of a man called Charon. He’s a killer, an assassin, the head of a murder organization that’s bigger than General Motors.”

Tim was puzzled. “Charon?” he asked. “What sort of name is that?”

“It’s a code name,” McGuffin explained. “It comes out of the Greek myths. You ever hear of Hades, the Greek underworld? In the old legends, it’s where people went when they died. Charon was the person who took them there. He was the ferryman of the dead.”

The sun must have gone behind a cloud. For the first time that summer I felt cold. Maybe it was the breeze coming in through the bullet hole.

“Nobody knows who Charon really is,” McGuffin went on. “He can disguise himself at the drop of a hat. They say he’s got so many faces his own mother wouldn’t recognize him.”

“Do you know his mother?” Tim asked.

“No.” McGuffin took a deep breath. “There’s only one way to recognize Charon,” he said. “He’s lost a finger.”

“Whose finger?” Tim asked.

“His own. He only has nine fingers.”

Tim smiled. “So that’ll help you finger him!”