The film opens in West Berlin during the Cold War, focusing on the fracturing marriage between a spy returning from a mysterious mission and his wife, who reveals her desire to leave him for another man. The husband's attempts to understand her motives uncover a profound and disturbing change in her behavior, leading him to question her sanity and fidelity. As he delves deeper, he discovers the existence of a secluded apartment that his wife frequents, which holds the key to the uncanny shift in her demeanor.

As the narrative unfolds, the personal and psychological turmoil escalates against the backdrop of a divided Berlin, symbolizing the broader themes of separation and alienation. The wife's increasingly erratic and violent actions suggest a deeper, possibly supernatural influence, intertwining her personal descent with a metaphorical representation of societal and existential angst. The husband's journey to uncover the truth leads to encounters with a series of enigmatic characters, each adding layers to the unfolding mystery of his wife's transformation. The film masterfully navigates the thin line between reality and madness, leaving the audience questioning the nature of love, identity, and possession itself.