Un rituel occulte qui tourne mal. Un monstre à la ferme. Deux morts dans deux villes situées dans deux pays vastement éloignés engendrent l'apparition de monstres horribles.

Les Johansen ont du mal à rester soudés sous la pression croissante de l'enquête sur la mort d'Ingrid. De leur côté, Rachel et Toby font face aux conséquences de la mort de Joy.

Rachel se voit confier la tâche délicate de recruter Toby dans la Fondation. Karl retrouve Mette, la sœur de sa défunte épouse, ce qui provoque des frictions dans sa relation avec sa fille Astrid.

Les Johansen s'apprêtent à enterrer leur matriarche. Les membres de la Fondation, eux, se préparent à un rituel obscur qui, espèrent-ils, mettra fin à la Décadence.

Après que le conflit entre Toby et la Fondation a atteint son paroxysme, la disparition des enfants plonge la vie des deux familles dans le chaos et le désespoir.

Les Johansen et les Hernandez voient leur vie quotidienne se détériorer encore plus tandis que la disparition de leurs enfants vient compliquer des relation déjà conflictuelles.

Astrid est confrontée à des preuves qui lui font craindre d'avoir fait du mal à son fils. Les étincelles fusent lorsqu'Eric se rapproche de Krista alors qu'ils recherchent Faith au sein de la Décadence.

Un rituel brutal promet de montrer à Rachel où se trouve sa fille. Karl s'inquiète de plus en plus de la fascination d'Eva pour la violence et du secret macabre que cache Mette.

Tandis que Rachel s'enfonce davantage dans les méandres de la Fondation en quête de Faith, la situation entre Karl et Mette s'envemine du côté nordique.

Karl must finally face the greatest tragedy of his life. Rachel finds herself on the outs from the Foundation for the first time and is confronted with her failure as a mother.

Astrid and Brit grieve their past while Eric faces a sex-magic ritual to protect himself from The Withering. Orson and Faith are returned unexpectedly, but not unscathed.

Astrid and Rachel become connected and work together to find out the identity of the mysterious "Lady in the Woods," the woman they suspect kidnapped their children.

The two families struggle with the bizarre changes their children have undergone. At the Foundation, Xavier faces the consequences of having brought Rachel into the fold.

The families contend with their children's increasingly disturbing behavior as they close in on a Foundation heretical sect that may be the source of their children's troubles.

With The Heralds unmasked, Astrid and Rachel must work together to apprehend them and stop their children's increasingly disturbing behavior.

Rachel and Astrid decide what to do with the Heralds, but then the monsters set their sights on the children, while Hope's Junction and Stilledan are plunged into complete chaos.

The two familles struggle to protect their children from the monsters—and the townspeople who believe Orson and Faith are the source of the horror they're all experiencing now.

Faith wields an otherworldly power, causing some townspeople to want to kill her and others to worship her as their new goddess. Astrid and Haugen figure out how to save Orson.

Relationships come to a head as Astrid faces Haugen, Brit faces herself, and the Hernandezes face each other -- and the foundation.

Eric faces the ultimate test of his loyalties. Brit confronts her self-destructive nature. Rachel takes control of her relationship to the Foundation. Astrid deals with Haugen.

Astrid and Rachel must face their demons to determine If they can save their children - or themselves - from the horrors of The Withering.