When John le Carré was running agents for the British secret intelligence service MI6 in the early 1960s, there were certain qualities he looked for in a candidate. Gregariousness, cocktail party charm, the ability to hold one’s drink — all of that mattered, of course. But above all, what le Carré wanted was “a sense of larceny,” as he explains during an interview at his north London home. “Somebody who enjoys the adventure and is not scrupulous about small stuff.”

In his new novel, “Agent Running in the Field” — set in modern-day Britain — the main character, Nat, is called out by his daughter about his lack of ethics. “For the sake of a country that you have serious reservations about, even very serious, you persuade other nationals to betray their own countr ies,” she tells him. Nat counters with an argument which le Carré admits is similar to his own: “I don’t think I persuaded anybody to do anything they didn’t want to do,” le Carré says. “I think I enabled them to do it and provided the protection.”

This morally murky world of spying is where le Carré continues to make his literary mark. “Agent Running in the Field,” which Viking will publish on Oct. 22 , is his 25th novel. It comes only two years after his last, “A Legacy of Spies,” and shows that, approaching his 88th birthday, the author isn’t exactly slowing down.

Image John le Carré’s “Agent Running in the Field” comes out Oct. 22. Credit... Sonny Figueroa/The New York Times

“I have no real leisure activity,” le Carré says. “I am dismayed when I’m not writing, completely content when I am. I also find, thus far, that I’m unaware of any relaxation of my talent. I also am stimulated and appalled by the path my country has taken.”