In the conclusion of the four-part story "The Massacre of St. Bartholomew's Eve," The religious differences that have suddenly cropped up between the Doctor (
William Hartnell) and Steven (Peter Purves) serve to heighten Steven's feelings of isolation. Of far greater importance, the Catholic hierarchy of 16th century Paris prepares its final fatal assault on the Huguenot population.
Jackie Lane joins the cast in the role of the Doctor's new travelling companion Dorothea "Dodo" Chaplet. Written by John Lucarotti and Donald Tosh, "Bell of Doom" first aired on February 26, 1966; this episode apparently no longer exists. ~ Hal Erickson, All Movie Guide