Summary
Highlights
Vanessa is lost in grief after her son Obe's death. A bird hitting her window, which her husband Alex interprets as a new beginning, doesn't comfort her. She visits Obe's empty room, overwhelmed with sadness. A discussion with Alex and his brother Martel reveals disagreements about their father's strange beliefs and the possibility of selling the house, which Vanessa opposes, especially if it means forgetting Obe.
Vanessa goes hiking and encounters an almost identical version of herself in the woods, who shoots her in the leg. Back home, she tells Alex she saw a bear, but he recognizes her distress, reminding her of Obe's death. Alex tries to console her, attributing Obe's accident to the other driver, but Vanessa believes she was at fault.
Vanessa's anxiety grows as she struggles with the image of her doppelganger. She starts noticing peculiar changes around her: Martel's hand magically heals, then a different version of Martel appears with a bandaged hand. These events lead her to believe she is not in her original reality. She returns to the woods, where she experiences strange loops and disappearances of her markers, confirming her disorientation.
Vanessa tells Alex about her strange experiences, but he dismisses them, suggesting she's lost or hallucinating due to Obe's death anniversary. An argument ensues, with Alex believing Vanessa needs help and offering her blue pills instead of her usual yellow ones. Later, she escapes her house, which she realizes is not her own, and returns to the forest. There, she meets an alternate Alex, a physicist, who explains they are trapped in multiple universes, each with subtle differences. He's been searching for his own lost Vanessa and confirms that in all universes he's visited, Obe is either dead or nonexistent.
Vanessa and Alex devise a plan to use fishing wire to navigate between realities. They visit a different house, where they encounter Martel, who, in this reality, caused the accident that killed both Alex and Vanessa, who was pregnant. Guilt-ridden, this Martel mistakes them for ghosts. After setting up their wire and a secret code, Alex departs to explore further, sharing a passionate kiss with Vanessa.
Alex returns, confirming his identity with their code. He recounts seeing a happy, childless version of themselves. He plans to use explosives to close off previously visited realities. That night, Vanessa follows a fishing wire to another reality, finding an Alex who doesn't recognize their code. She realizes this is her original Alex when he correctly identifies Martel's injured hand. However, her attempt to explain the multiverse leads to a violent reaction; Alex hits her, believing she's an imposter.
Bound, Vanessa tries to convince Alex she's his real wife, but he reveals he killed his Vanessa because he thought she was delusional after being shot in the leg. Martel, swayed by Vanessa's multiverse theory, tries to stop an enraged Alex, leading to Alex's accidental death. Martel then commits suicide. Devastated, Vanessa encounters a dead Alex without a wedding ring, implying another Alex took his life. She then sees a happy version of her family but leaves them alone. The divorced Alex returns, having killed another version of himself to take his place. He encourages Vanessa to do the same to find a world where Obe lives, warning her it's 'kill or be killed' and to choose wisely.
Alex plants explosives to seal off realities and leaves Vanessa to find a new one. She encounters another depressed Vanessa, the estranged wife of divorced Alex, who doesn't want to return to him after he pulled the plug on their son. In a struggle, Vanessa accidentally kills her. Exhausted, she crosses into a final reality. She wakes up to a bird hitting the window, a cheerful Alex, and Martel. This time, when she goes to Obe's room, it's filled with toys, and she hears her son calling her name, indicating she has found a reality where Obe is alive.