Carlo Bontempi, a skilled surgeon from Turin, is devastated by the death of his wife, Adele. After two years of mourning, he decides to propose to Margherita Bosio, Adele's best friend. Just as he feels ready to move on, Nina Caruso, a troubled con artist posing as a medium at a party, disrupts his life. During a staged séance, Nina unexpectedly falls into a trance and speaks a phrase only Adele would know. Carlo rushes to help her, but she escapes into the rain before he can ask her name. He finds one of her earrings and sets out to find her.

Starting a romantic relationship, Nina and Carlos quickly grow close. They meet Madame Margot, a psychic with an esoteric shop. When Nina falls ill again, Carlo rushes her to the hospital, discovering her unusual kidney failure isn't viral. Meanwhile, Commissioner Barbera warns Nina and her accomplice Annabella about their fraudulent schemes. Despite the concerns of his best friend Tommy, his father Giorgio, and his girlfriend Margherita, Carlo takes Nina to his villa by Lake Maggiore to connect with Adele's spirit, where she enters a trance.

Carlo and Nina's attraction grows, but Nina is troubled by Adele's lingering presence and chooses to stay away, fearing Adele wants her death investigated. Carlo is fixated on his wife's dubious test results, raising concerns for his colleague Melodia and fiancée Margherita. While getting supplies from the restaurant's freezer, Nina enters a trance and realizes Adele was poisoned with mercury. She rushes to Villa Bosio, where Margherita and Carlo's engagement party is happening, to share her discovery. Carlo later confirms this when he finds hair on a brush that belonged to Adele.

Carlo tells Margherita that Adele's death was caused by long-term mercury poisoning, not a virus. After discovering that Adele's medical records were altered, he reports this to Commissioner Barbera, who expresses skepticism and warns Carlo about Nina's past. Despite this, Carlo continues his relationship with Nina. They meet at the Egyptian Museum, where they learn that Irma Lovric, the main suspect in Adele's case, is employed. Irma denies any involvement in the poisoning. After their visit, Carlo and Nina share a kiss, but Nina quickly feels regret and runs away, narrowly avoiding a speeding car.

Who tried to run Nina over near the museum, and who intervened to save her? The investigation is uncovering key details. A benefactor has made substantial deposits into Irma's account, Adele's nurse. Carlo's wife's computer also has a folder linked to Choco Elly, a dubious cocoa import business. Carlo is interested in exploring the Bosio family's connections. Meanwhile, Margherita, feeling envious, confronts Nina and attempts to alert her boyfriend, viewing Nina as a fraud. However, Carlo, having revealed important truths about his father, finds himself increasingly attracted to Nina, leading to a romantic moment at the family villa. Shortly after, while swimming, Nina dives into the lake and discovers a gun.

Who did Adele entrust her gun to for Nina? After Nina hands it over to the police, she starts getting threatening messages. Carlo finds out that Nina and Annabella were watching him and Margherita trying to steal a valuable diamond from the Bosio home. Despite Nina's claims of innocence, Carlo is doubtful and, with Tommy's help, reports both her and Annabella to the authorities. Meanwhile, Margherita's grandmother, Mrs. Ortensia, passes away and visits Nina in a dream, urging her to find a specific Japanese green tea that Adele loved. Commissioner Barbera uncovers evidence suggesting Tommy may have tried to run Nina over and discovers that the gun retrieved from the lake belongs to him. As a result, Tommy becomes the prime suspect, leading to his arrest for the attempted hit-and-run and the mercury found in the tea he gave to Adele.