As Christian struggles with his past, Hanna contemplates throwing him in at the deep end once again — as an undercover agent in a dangerous bid to infiltrate The Circle.

A crime wave has taken hold of Oxford. A debauched group of undergraduates are wreaking havoc across town, and the death of a uniformed policeman sends shockwaves through Castle Gate.

Ridley always suspected the initial investigation into the unsolved case was flawed, and that the wrong man was tried for Hannah Lindsay's abduction. As they delve deeper, the discovery of another body leads to a shocking secret.

Hannah and Billy try to uncover the leak at Police HQ which resulted in the deaths of several of their colleagues. When Hannah’s obsession concerns her boss, she and Billy pursue their own “unofficial” investigation. Christian and Bianca find that their hideout isn’t as safe as it seems. Under pressure to move her cocaine, Dubravka meets with an intermediary who makes her a tempting offer.

A murder in a college garden leads Endeavour to investigate a celebrated Oxford orchestra but, when a second tragedy hits, he discovers a story the ensemble would sooner forget.

Retired Detective Inspector Alex Ridley is called back to advise on a complex and compelling murder case by his replacement and former protege DI Carol Farman. Carol is keen to access Ridley’s unique insight into crime-solving which served them so well in the past, but the investigation takes a dark and unexpected twist.

Tom’s letter to Lady Bellaston threatens to sink his prospects with Sophia. A swordfight puts him in even deeper trouble. A secret emerges.

Tom is lured to a masquerade by an insatiable paramour; complications develop. Blifil and a loathsome lord try to compromise Sophia.

Tom is banished by Allworthy. Meanwhile, Sophia flees her impending marriage to Blifil. Adventures ensue, including fateful encounters at two inns.

As Trixie and Matthew’s wedding officially begins, a series of small and great disasters threaten to impede the day. A horrific car crash turns into a race against time. Sister Julienne hatches a plan to save Nonnatus House once and for all.