“About DS Fowler,” she clarified, as though Joel were slightly slow. “He said you probably wouldn’t take my word that I was here on his behalf. He told me to say—let me get this right—‘dolce Torino’. I suppose that’s Italian for something? Anyway, he said that would prove I was from him, a sort of password. It’s all terribly cloak and dagger.”

That was the chocolate sweet Aaron had watched Joel eat with an expression of such naked longing that Joel had all but thrown himself on the table there and then. “Yes, I see,” he said carefully. “Why did he give you a password? I mean, why are you here, and not him?”

“Because he’s in rather a lot of trouble,” Constable Challice said. “May I sit down?”

“Of course, sorry. Tea?” he added automatically.

“He said you’d thrust tea on me,” Challice remarked. “He said you wouldn’t be able to help yourself. If the house was burning around your ears, he says you’d put a kettle on the flames.”

“Yes, all right, you’re definitely from him,” Joel muttered. “What trouble? Is he all right? How do you take it?”

“No tea. Sit down.” The instruction came in the sort of voice that took a man right back to school, and Joel dropped into the nearest chair as though she’d cut his hamstrings. Challice took the other seat and folded her hands neatly in her lap.

“Well,” she said briskly. “First of all, DS Fowler has given me a series of quite remarkable allegations about DDI Colthorne. I understand you know that.”

“Yes.”

“DS Fowler believes that the DDI was behind the murder of Gerald Marks, because he feared Marks had something on him. Was perhaps even blackmailing him.”

“Yes.”

“Do you believe that?”

“DS Fowler believes it, which is what matters,” Joel said. “He’s the copper, he knows about the case, and he thinks it’s what’s going on.”

“And what do you think?” she said implacably.

“I think he’s an honest man. I know that someone is leaning on me to get at him. And I understand this started after the Marks murder, which Colthorne told DS Fowler to stop investigating. So yes, I believe it.”

She nodded slowly. “Interesting. Because the thing is, DDI Colthorne has accused DS Fowler of gross misconduct, on both personal and professional levels. He’s offered to let Mr. Fowler resign quietly for the good of the Met, if he signs a full statement admitting to disgracing his office. If he doesn’t resign, the DDI will take it to a formal disciplinary.”

“He’s trying to shut him up. Isn’t that obvious?”

“Unless DS Fowler knew he was going to be accused, and trumped up this story against the DDI first in an effort at self-protection.”