Mikael, Ulrich Thomsen, has taken leave from work in search of a life change. He stays at home with his wife Sigrid, Paprika Steen, and their daughter Selma, Emma Sehested Høeg. Life feels unsettled, and Mikael’s curiosity nudges him toward a risky choice: he volunteers to join an experimental anti-depressant study run by Sigrid’s brother, Frederik, Lars Brygmann. He keeps this secret from his wife and daughter, documenting his experiences in a diary as the days pass. The diary becomes a window into a gradual loosening of boundaries; the pills seem to unlock a freer version of himself, a version that questions rules and fairness and pushes him to imagine a different life. As the effects intensify, Mikael moves away from the family home to his mother’s old rural house, hoping the change of scenery will help him understand what he’s feeling.
The experiment spirals out of control when several subjects begin acting violently, including Mikael. Frederik’s team shuts down the trial, but Mikael clings to the sense of liberation the pills give him and begins to hide continuing use. The drug’s pull deepens his detachment from those around him and corrodes the trust in his marriage. At home, his behavior turns increasingly abusive and manipulative: he gaslights Sigrid, first by turning up the water heater and scalding her in the shower, then by releasing rats into the bedroom while she sleeps. The power dynamics deteriorate as he crosses boundaries with others, including a young woman he pressures into exposing herself during a ride, and he seduces Frederik’s wife, further severing the fragile ties the family has left.
Mikael’s fear of admitting what he’s done grows, and he begins to contemplate confessing to Frederik. Before he can act, Frederik reveals a devastating truth: Mikael has been taking placebo pills all along, a result of the scientists’ decision to spare his brother-in-law from unsafe drugs. The reveal shatters Mikael’s sense of control and accountability, and the tension inside the house reaches a breaking point. Selma discovers Mikael’s diary, and in a panic he locks her in the sauna, hoping to keep her from exposing him. Sigrid, who has been given a sleeping pill, regains consciousness, confronts him, and a violent struggle ensues that ends with Mikael punching her and locking her in the chest freezer. Realizing the nightmare he’s creating, Mikael makes the choice to run, leaving his wife and daughter trapped in the danger he has unleashed. Sigrid somehow escapes from the freezer and frees Selma, but the family remains fractured and at risk.
The film closes with Mikael at a train station, having visited his mother in a nursing home, and facing the stark truth of his actions. He speaks of his ongoing sadness and the lingering difficulty of understanding when things began to unravel, acknowledging that the memories themselves are painful to confront. The final moment lingers on his uneasy resolve, a man trying to piece together why he took things so far and whether there might ever be a way back from the consequences of his choices.
