Three-part ITV drama about real-life killer Malcolm Webster and the crimes he committed in the 1990s. When his wife Claire (Sheridan Smith) becomes suspicious about unpaid bills and credit card debts, Webster (Reece Shearsmith), at the time working as a nurse, poisons her and deliberately crashes their car, setting it on fire and leaving her inside. Three years later he marries Felicity Drumm (Kate Fleetwood) in New Zealand and soon after begins plotting her murder in order to receive money from forged life insurance policies. His plan fails, however, and with Felicity now aware of Webster's true nature, he leaves the country and moves onto a potential third victim, Simone Banarjee (Archie Panjabi). Will investigating Detective Inspector Charlie Henry (John Hannah) catch Webster before it's too late?