As Endeavour sees in the new year – 1970 – at an opera house in Venice, a murder on an Oxford towpath speaks to Thursday's intuition, and convinced he has the man responsible, he vows to bring him to justice. Returning home, Endeavour makes a new acquaintance, and old friendships show signs of strain. Later, when an exciting new educational television programme appeals for Academic presenters, a contentious college project develops into a fatal battle of the sexes. On investigating, Endeavour and Thursday discover a potential link between the department and a young woman's troubling premonitions.

As campaigning for the 1970 general election gets underway in Oxford, racial tensions escalate in the city and a clash between two young rival gangs results in tragedy. Initial investigations lead Endeavour and Thursday to the door of a familiar face, where they discover the influence of the British Movement, a right wing organisation hoping to win an Oxford seat. Elsewhere in the city, tragedy strikes a second time, this time an Indian restaurant, where a customer's mysterious disappearance and a shocking murder put even the strongest family loyalties to the test.

When Endeavour is called to investigate what at first appears to be a freak accident at Lady Matilda's College, he uncovers a potential link between a series of peculiar incidents across Oxford, and despite Thursday's skepticism, becomes convinced the accidents are the result of foul play. Lady Matilda's meanwhile, is in the midst of a referendum campaign which will decide whether or not the college should become co-educational, and when one of their own is attacked while walking alone on the towpath, the female students become more determined than ever to keep the wolf without the citadel.