The crime drama's fourth season begins with Dr. Temperance Brennan (Emily Deschane) and Seeley Booth (David Boreanaz) lecturing to their respective peers in London, but their trip is extended after they're drawn into the murder of a wealthy American's daughter. Other investigations spin around the slayings of a reality-TV host, a veterinarian, a pastor, a sculptor, a former Marine, conjoined twins, an ice-hockey player and a bride-to-be. Cycle 4 also features the return of the Grave Digger, a sepulchral serial killer who may be targeting Booth.