Baron Samdi is the voodoo spirit of the dead that Emmanuel Jannite invokes when he follows his love, Yveline Lafond, to Kembleford. Lafond is working as lead singer in a Haitian jazz band. The band leader in love with Lafond is found dead in a swimming pool poisoned, and Jannite dies following a police chase. Inspector Mallory believes the case closed but Father Brown's snooping uncovers the killer. As he confronts him, Brown collapses as the killer tells him he has already poisoned him that morning.