THE TARDIS ARRIVES IN PARIS IN AUGUST 1572, a time that excites the Doctor as he believes it will give him the opportunity to meet the scientist Charles Preslin. The Doctor is concerned about leaving Steven Taylor on his own in a strange place, but his companion eventually persuades him that he will be safe for the day and that he should look for Preslin.
As the Doctor tries to locate the scientist, Steven becomes involved with a group of Huguenots led by Nicholas and Gaston, who explain that they are French Protestants who face oppression from the Catholic majority. They come to the aid of Anne, a terrified serving girl who believes she has overheard plans for a mass slaughter of Huguenots in the city.