The central mystery of "Forgotten Love" is the connection between Antoni Kosiba and Marysia. After a motorcycle accident nearly kills Marysia and Count Leszek, Antoni performs a life-saving, albeit primitive, brain operation on her, deepening their inexplicable bond. Meanwhile, Count Leszek's mother, the Countess Czyńska, attempts to sever the relationship by lying to her recuperating son that Marysia died and paying Marysia to disappear.
To protect Marysia from the Countess's threats, Antoni turns himself in for practicing medicine without a license. The climax occurs in the courtroom. When Professor Dobraniecki, Wilczur's former colleague, is brought in as an expert witness, he is asked to examine the surgical tools Antoni allegedly stole. Upon seeing Antoni, Dobraniecki dramatically identifies him as the long-lost Professor Rafał Wilczur. Overwhelmed by the testimony and seeing Marysia in the gallery, Rafał's memory floods back, and he recognizes her as his daughter. The reunion is the emotional catharsis of the film. The ending sees all conflicts resolved: Rafał's name is cleared, and the film concludes with a joyous double wedding, where Rafał marries the loyal Zośka, and Marysia marries Count Leszek, who has reconciled with his family.