The TARDIS materialises in Paris in the year 1572 and the Doctor decides to visit the famous apothecary Charles Preslin. Steven, meanwhile, is befriended by a group of Huguenots from the household of the Protestant Admiral de Coligny. Having rescued a young serving girl, Anne Chaplet, from some pursuing guards, the Huguenots gain their first inkling of a heinous plan being hatched at the command of the Catholic Queen Mother, Catherine de Medici.
| Directing | Paddy Russell | Director |
| Writing | John Lucarotti | Writer |
| Writing | Donald Tosh | Writer |
| Art | Michael Young | Production Design |
| Production | John Wiles | Producer |
| Writing | Donald Tosh | Script Editor |
| Writing | Gerry Davis | Script Editor |
| Sound | Pierre Arvey | Music |
