After the mysterious disappearance of a teacher, Endeavour finds himself undercover, investigating the dark world of a public school. When a body is unexpectedly discovered, Endeavour has to question who he can trust – and uncover the truth about the crimes before more people are hurt. Thursday is determined to solve the ongoing unsolved murders linked to Eddie Nero, and charges Fancy with tracking down the elusive Cromwell Ames. Meanwhile, Thursday’s life is turned upside down by the return of his brother, and Endeavour looks towards the future with the possibility of a new relationship.