When a librarian is gruesomely murdered at the Bodleian, Endeavour and Thursday have little to go on besides a set of muddy boot prints. With the two main suspects having their own motives for killing the librarian, Endeavour digs deeper into their backgrounds, tracking a trail that appears to connect to seemingly innocent college bequest.

With the Cowley team scattered across Oxfordshire, Endeavour finds himself policing a lonely country patch, and back in uniform. His day job is a monotonous investigation of missing livestock and stolen tractors. But when he discovers the dead body of a missing schoolgirl, it opens this quiet backwater to the roar of Castle Gate CID – now staffed by Thursday and an old adversary, the newly promoted DCI Ronnie Box, alongside sidekick DS Alan Jago.

The murder of a chocolate factory owner during a local hunt leads Endeavour to the sleepy village of Chigton Green. When he learns of a vicious campaign of gossip and rumour, it seems likely that two murders are connected. One of the targets, a beautiful, single mother, captures Endeavour's attention, giving him food for thought about the future.

As the highly-anticipated moon landings of Apollo 11 draw near, Endeavour finds himself investigating the death of a promising young astrophysicist and his girlfriend. Their deaths seeming to be a result of a tragic car accident on first inspection, with the clues pointing to foul play, Endeavour enlists the help of an injured Thursday to uncover the truth.