Frankie Morrison, portrayed by Jack McElhone, is once again relocating with his mother, Lizzie, and grandmother, Nell. Lizzie assures Frankie that this will be their final move, yet Frankie can't help but note, "she says that every time." As they begin to settle into their new flat, we discover that Frankie is deaf, an aspect that shapes his experiences and interactions.
In a reflective voiceover, Frankie writes letters to his father, Petty Officer Davey Morrison, who serves aboard the Accra. It's evident that Frankie is accustomed to writing, collecting stamps from this correspondence, which, unbeknownst to him, is primarily from his mother. The absence of his father casts a shadow over their lives, and a personal ad concerning Lizzie heightens the family's apprehensiveness about being discovered.
At his new school, Frankie faces the all-too-familiar sting of bullying, notably from Ricky Munroe, the chief instigator. However, he also finds camaraderie in Catriona, a classmate who stands by him. As tension rises, a bet is made with Ricky, who provocatively claims that Frankie's father won't show up when the Accra docks.
As the arrival date approaches, Lizzie's frustration escalates, prompting her to venture into a local pub, only to be left feeling disheartened. Desperate for assistance, she confides in her friend Marie, who suggests a potential stand-in for Frankie's father. Lizzie meets the man, passing along the heartfelt letters Frankie has composed to his dad.
The day of the ship's arrival sees Frankie disappearing for hours, only to return to find the surrogate father waiting at the flat. This mysterious man surprises Frankie with a book chosen based on Frankie's letters, igniting a spark of joy within him, which prompts a heartfelt embrace.
As Frankie revels in his triumph with Ricky at football tryouts, the pair decides to extend their time with the stranger, leading to a delightful day of bonding by the harbor. Lizzie, initially hesitant, gives in and embraces this fleeting familial connection. Yet, as the day unfolds, she reveals the pain behind Frankie's deafness—the result of abuse from his real father.
In a poignant twist, Lizzie confronts her past when she reaches out to her sister-in-law and ultimately visits her ailing husband, Davey, in the hospital. He wishes to see Frankie, yet Lizzie's refusal exposes the deep-rooted anger and trauma that drove her away. After his death, Lizzie breaks the news to Frankie and goes to stop the payments on the PO box holding his letters. Here she finds one last message from Frankie, addressed to the stranger whom she hopes will come back into their lives, revealing a touching acknowledgment that his "real Da" has passed away.
