A recently released convict, Peter Glahn, returns to his home in the peculiar land of Mandragora, a place where daylight never fades. While traveling back on a ship, Peter shares a fleeting moment of romance with Juliana Kossel. Upon his arrival, he visits the family ostrich farm managed by his sister, Amelia. Amelia is deeply infatuated with the enigmatic Dr. Isaac Solti, a gentleman scientist with manipulative tendencies. Tension arises when Cain Ball, Amelia's laborer, confronts her regarding her commitment to selling the farm.
As Peter wanders into the forest for a hunting expedition, he encounters a pregnant woman named Zephyr, who, despite her marital ties, finds herself drawn to him. In desperation, Zephyr seeks the favor of a stone statue of the goddess Venus, offering her wedding ring as a token in hopes of winning Peter's heart. A subsequent meeting leads to a tender embrace between Peter and Zephyr, yet both acknowledge their pre-existing loves—Peter’s for Juliana and Zephyr’s for her husband.
Meanwhile, Dr. Solti has his own strange relationship with the statue of Venus, which cursed his leg, leading to an amputation after it fell upon him. During a picnic, Peter and Amelia encounter Solti and Juliana, who is revealed to be under Solti’s hypnotic control, sparking jealousy in both Peter and Amelia. A confrontation ensues when Peter, enraged by Solti’s manipulations, makes an attempt to attack him, but his efforts prove futile against Solti's artificial limb.
The plot thickens as Amelia grows paranoid, believing Cain is plotting against her, leading her to metaphorically slam a nail into his skull, set him ablaze, and unleash a series of torturous nightmares upon him. In a shocking confession, Zephyr reveals she inadvertently caused her husband's death by luring him into a snake pit.
As Peter and Juliana's romance rekindles, their newfound affection is soon tarnished by Peter's jealousy. In frustration, he summons the spirits of the forest to deal with his adversaries, but they only manage to droop a little. In a tragic turn, Zephyr confronts the statue of Venus to reclaim her ring, only to be crushed under its weight. The remnants of Cain's twisted fate play out as he hallucinates the deceased cast aboard a boat before succumbing to his injuries. Ultimately, the trajectory of both Solti and Juliana sees them leaving Mandragora, with Juliana asking Peter for a keepsake—his dog, Aesop. Torn between attachment and loss, Peter reluctantly kills his dog before seeking refuge with Amelia in a wintry cave, leaving the haunting shadows of their past behind.
