Jack Walsingham's comfortable life is under pressure. With his bookshop going broke and past indiscretions catching up, Jack begins to dabble in embezzlement. Meanwhile, his wife Thea, frustrated by a dead end in her career, is experimenting with some genteel theft of her own. But soon the couple are out of their depth, blackmailed by a figure from the past and implicated in two grisly killings. Their salvation comes in the form of Detective Sergeant Fiona Salmon, a recently widowed book-loving gym addict on the edge of an emotional melt-down. A bizarre triangle develops in which Thea, Jack, and Fiona each find their own version of redemption in the face of betrayal and infidelity. An Englishman's Guide to Infidelity is at once a psychological thriller, a crime mystery, a dark comedy, and a love story.