After a young Secretarial student called Margaret Bell dies at home suddenly, Endeavour believes that there is more to the case than the initial medical verdict of 'heart attack'.

There is a new kind of killer haunting the Oxford twilight. Endeavour and Thursday find the city's dreaming spires giving way to waking nightmare.

HRH Princess Margaret is due to visit Oxford to unveil the British Imperial Electric Company’s latest weapon of mass destruction at a Cowley factory. Endeavour who is still stuck doing General Duties, is excluded from the event. After the ceremony comes to a close he finds himself deeply embroiled in the affairs of the factory and its owners, the dysfunctional Broom family. Percy Malleson, has been found murdered in a secluded area of the shop floor in the factory. One of his his colleagues, Lenny Frost, is the main suspect as there is bad blood between them resulting from an industrial accident.

A hit and run accident claims the life of an eminent Classics Professor forcing Endeavour and Thursday to each face their past. Not every story has a happy ending.