1908, the height of the British Empire. Clara's autonomy is shattered when her long-absent husband summons her to join him at his eerie sect's headquarters, insulated on a sparsely inhabited island in the Bahamas.

After a harrowing sea voyage, Clara and her children disembark into an unfamiliar landscape and climate. The children explore the marvels and mysteries of Andros Island and develop friendships with a Bahamian family, while Clara struggles to find her place as a woman within the cult.

But what seems at first to be a spiritual haven for Clara reveals itself to be a monster-worshipping cult intent on draining her family of more than their fortune.

Must Clara give up her quest for independence to protect her children from the cult's depraved attempts to consume their life essence?