“Reign” fans will be in for an early Halloween treat when episode 4, “The Lamb and the Slaughter,” airs on the CW next Thursday. Mary (Adelaide Kane) and Francis (Toby Regbo) have faced their fair share of drama in the past few weeks – from an illegitimate child to the plague – but things will take an otherworldly turn in the coming episode.

As “Reign” viewers saw in episode 3, Francis began to fear that spirits of the dead were beginning to walk among the living. He wanted to keep his theories a secret, but it looks like Bash (Torrance Coombs) will find out in episode 4.

The synopsis for the episode teases that Bash and Lord Condé (Sean Teale) will be called in to investigate when a “shepherd is attacked by shadowy riders.” But the riders might be more than unruly countrymen. Bash and Lord Condé realize that they may have angry spirits on their hands or potentially be at the beginning of a religious war.

Meanwhile, Mary will continue to work on her strained relationship with Lola (Anna Popplewell) after the birth of Francis’ illegitimate son. With the child’s christening on the horizon, the baby will serve both as a “bond” and an “obstacle” between the estranged friends.

Elsewhere, Mary’s other former lady-in-waiting, Greer (Celina Sinden), will find herself facing her ex-lover when Leith (Jonathan Keltz) is forced to return to the castle. Viewers will remember that the pair has been dealt some bad luck in recent episodes. Greer’s fiancé, Lord Castleroy (Michael Therriault), left her at the castle to tell his children of the death of his eldest daughter, Yvette (Sarah Winter). And Leith had his land stripped from him by Francis. The synopsis hints that Greer will “take control of her future” with Leith’s arrival.

Finally, more trouble will brew in episode 4 of “Reign” when Lola suspects something is “awry” when Lord Narcisse (Craig Parker) introduces his “familiar new bride.”

Season 2 episode 4 of “Reign” will air on the CW on Thursday, Oct. 23, at 9 p.m. EDT. What do you think is suspicious about Lord Narcisse’s new bride? Tweet your thoughts to @AmandaTVScoop.