The early days of a young Endeavour Morse, whose experiences as a detective constable with the Oxford City Police will ultimately shape his future.
Endeavour learns he'll have to take on a young new apprentice, but the pair barely get time to say their hellos before being thrust into an investigation as a number of sadistic murders accompany the auction of a Faberge egg at an Oxford college.
Hollywood glamour comes to Oxford as the stars of a new horror movie sequel begin filming in the city. Meanwhile, the unexplained poisoning of a former detective sergeant leads Endeavour and Thursday to a local cinema, which is playing host the film's stars in a special event.
The railway takes centre stage as Endeavour investigates the disappearance of a local woman - with initial fears linking it to the unsolved murder of a teenager, killed several years earlier. Endeavour puts the missing woman's last known movements under scrutiny, while Thursday is absorbed in the investigation of a lorry hijack which he suspects is linked to local gangster Eddie Nero.
A photoshoot on an army base turns sinister when one of the models is found dead, and the investigation is complicated when Sam Thursday is revealed to be involved. With Thursday side-lined by protocol, Endeavour and Strange take the lead on the investigation for the first time without their mentor. Tensions rise, and the pair clash as their differing opinions push their friendship to breaking point.
An assassination attempt at an international sporting event opens a new case for Endeavour and Thursday, but their investigation is quickly brought to an unexpected end. While Thursday wants to step away, Endeavour is determined to find out more, and secretly undertakes to discover the truth. He soon finds himself embroiled in the dark dealings of espionage, big business and a long-held secret that goes to the very heart of the Oxford community. While Endeavour chases down the real story behind the assassination, Thursday works closer to home, attempting to protect a battered wife from her violent husband. When tragedy strikes, Thursday has to make a tough moral decision about how to administer justice.
After the mysterious disappearance of a teacher, Endeavour finds himself undercover, investigating the dark and secret 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.
Meanwhile, with news that Cowley Station is due to close, Thursday is determined to solve the ongoing unsolved murders linked to Eddie Nero, and charges Fancy with tracking down the elusive Cromwell Ames. But when the investigation ends in disaster, Cowley CID find a surprising link to Endeavour's investigation at the public school. In the shadow of the tragedy, Endeavour and Thursday find some unexpected answers to their cases.