A homicide detective goes undercover to investigate a psychotherapist linked to a double murder case in London. Posing as a depressed patient, he enters therapy sessions and becomes entangled in the world of psychology and the nuances of human behavior. As he delves deeper, he uncovers an intricate web involving other patients and begins to question the boundaries between reality and delusion. The investigation leads him through various psychological labyrinths, drawing him closer to the truth but also compromising his mental stability.

During his covert operation, he encounters numerous unsettling revelations that shake his understanding of the case and himself. The psychotherapist's methods expose hidden facets of his psyche, causing him to lose grip on his identity. As the line blurs between his professional role and his emerging mental issues, his relationships and perceptions are put to the test. The complex interplay between the characters deepens, escalating tensions that drive the plot toward a gripping and unexpected climax.