Mary Hussain, portrayed by Joanna Scanlan, is thrown into a whirlwind of emotions when her husband, Ahmed, played by Nasser Memarzia, unexpectedly passes away one night. Following the funeral, Mary takes a closer look at Ahmed's wallet and uncovers an unfamiliar photo of a woman named Geneviève, brought to life by Nathalie Richard. Driven by curiosity and suspicion, she discovers a series of flirtatious text messages that Ahmed exchanged with this mystery woman.
Determined to find out more about Geneviève, Mary embarks on a journey across the English Channel to Calais. Upon her arrival, she is mistakenly identified as a cleaner by Geneviève, who welcomes her into her home. Living with Geneviève is her son, Solomon, played by Talid Ariss, with whom she seems to have a strained relationship. Unbeknownst to them both, they are unaware that Ahmed has died, and Mary cleverly conceals her true identity to dig deeper into the secrets that surround her husband's double life.
As Mary immerses herself in their household, she discovers numerous articles of Ahmed's clothing, stirring emotions within her. One day, while watching a home video featuring Geneviève, Solomon, and Ahmed, Mary experiences a jarring realization: Geneviève and Solomon are indeed Ahmed’s hidden family, a part of his life that Mary never knew existed.
When Solomon arrives home one day with a friend, Mary witnesses an intimate moment between them and, in their brief encounter outside, they share a connection over the theme of hidden relationships. As they speak, Mary shares stories of her own past with Ahmed, recounting how their love was once a secret too, filled with letters and audio tapes when he moved to Pakistan.
Conflict arises when Solomon confronts Geneviève, accusing her of infidelity and declaring his wish to live with Ahmed instead of moving away. In a dramatic confrontation, Mary learns from Geneviève that she was fully aware of Ahmed's other wife—Mary herself—yet chose to continue her relationship with him regardless. This admission leads Mary to impersonate Ahmed through text messages, stirring more chaos and emotion.
As the impending move draws closer for Geneviève and Solomon, Mary attempts to bond by cooking a meal. However, tensions escalate between Geneviève and Solomon, resulting in an outburst where Mary slaps Solomon, igniting Geneviève’s wrath towards her. It is during this confrontation that the truth spills out: Mary boldly reveals her identity as Ahmed's wife, prompting Geneviève to demand answers about his whereabouts. The situation escalates when Solomon, confused and distressed, connects the dots and learns that Mary has deceived him by masquerading as his father.
Fate brings the three women together at Ahmed's grave. Here, they unexpectedly discover shared grief, as they all pay respect not only to Ahmed but also to Mary’s late son, who rests beside him. Geneviève admits her jealousy toward Mary, revealing the complexities of their shared love for the same man. Shortly after, Mary hears the nostalgic sounds of one of Ahmed’s cassette tapes, which triggers a wave of emotions. Solomon offers to give it to her, yet in a moment of understanding, Mary encourages him to keep it instead, leading to a heartfelt embrace that signifies their shared bond over loss.
In a poignant final scene, the three of them venture to the White Cliffs of Dover, gazing out over the English Channel, united by their complicated, intertwined fates.
