Robert B. Parker has written five books starring Spenser, the tough Boston operator, a one-man army. In his new book, "Wilderness" …, a different hero is introduced—a man named Aaron Newman, a writer, jogger, big and strong but saddled with doubts of self and wife.

Jogging along peacefully one morning, Newman sees a murder and can identify the killer, who turns out to be a psychopathic gangster. He tells the police what he knows, but when the gangster threatens his wife, Newman recants his evidence. But can he now live with himself? And how does his wife, who can be very bitchy, feel about it?

Thus, while there is plenty of action in "Wilderness"—indeed, nothing but action—the book ends up as a psychodrama in which a married couple is put through unusual stresses, understanding each other a great deal more when everything is over. The writing...