At the start of the novel, the home life of Francois Mouret and his wife and cousin Marthe (née Rougon) is portrayed as a generally pleasant and relaxed existence.

Francois is slightly compulsive in his behaviour and Marthe clearly suffers from some sort of mental illness, which Zola intended to portray as a genetic consequence of the Rougon-Macquart family's tangled ancestry.

Slowly, it transpires that the mysterious stranger has arrived to try to win influence in the town for outside political forces (which never manifest themselves) through a series of Machiavellian intrigues, plots, slanders and insinuations; in the process of doing so, he proceeds to unravel the Mourets' lives to such an extent that the bewildered Francois is unwillingly and unnecessarily committed to a mental institution, while poor Marthe becomes obsessively religious, though whether her devotion is to God or Faujas becomes increasingly unclear.

The narrative is kept up at a tremendous pace and builds to a quite astonishing climax of violence and horror as Zola ends the novel in a near-apocalyptic fury.

A more modern retranslation was undertaken by Brian Rhys for Elek Books and published in 1957 under the more expressive but less faithful title A Priest in the House, but it is no longer widely available.