Don’t Let Him In by Lisa Jewell is a gripping psychological thriller about deception, trust, and the dangers of charm. The story follows Nina Swann, a recent widow who is drawn to Nick Radcliffe, a seemingly perfect man and long-time friend of her late husband — until her adult daughter Ash becomes suspicious of his motives and begins digging into his past. At the same time, Martha, a florist in a neighbouring town, begins to question the frequent absences of her own husband, Alistair, sensing there’s more to his story than he lets on. As Nina, Ash, and Martha’s lives intersect, they uncover unsettling truths that challenge their assumptions about love, loyalty, and vulnerability, revealing how easily someone can manipulate grief and trust. The novel is known for its twisty plot, dark characters, and tense domestic suspense that keeps readers guessing until the end.