Karen Olsen, who has been living with her mother and stepfather in Cleethorpes, returns to her home town of North Shields. Arriving at the quayside, she approaches the crew of a small fishing trawler and calls to her father, Alfie, who at first does not recognise her.

Alfie sends Karen to his home with his current partner Betty. Betty is hostile and suspicious of the newcomer, at first because she learns Alfie has been sending money for Karen's education, and later as rumours circulate that Karen is, in fact, a former girlfriend of Alfie, rumours fuelled by Betty's best friend Irene.

Alfie's boat, 'Sally' is in poor condition and the owner, Peter Parkin, is keen to sell it. Peter and Alfie argue, but Alfie hopes that a successful fishing trip will change Peter's mind. Alfie gathers his crew together - Dandy Mac (Irene's husband), Micky Molloy, and Yopper (on his first trip aboard) - and they set sail. Later, the crew is dismayed to discover that Alfie has brought Karen on board, with Dansy Mac being especially hostile. However, Karen proves to be a very capable crew member, and defiantly stands her ground, refusing to be intimidated by the men. Mickey admires Karen's spirit and they strike up a friendship.

During a storm, Dandy Mac suffers a head injury, and his behaviour during the rest of the voyage becomes increasingly unstable, culminating in an attempt to purge the boat of evil spirits with a firebrand. The trip is also failing to live up to Alfie's hopes, with the crew's efforts being poorly rewarded with two insubstantial catches.

Meanwhile, ashore, Betty is becoming increasingly agitated about Karen and searches her belongings, discovering photographs of Karen as a young girl with her father. Irene becomes worried for the safety of the crew as news of the storm arrives.

Back at sea, the final catch, containing few fish and a dead seal, proves to be the last straw, especially for Mickey, and Alfie sets course for home. Arriving back in port, Karen is attacked in the pub toilet by Yopper's girlfriend Tracey and two of her friends, but is rescued by Betty, who now knows that she is Alfie's daughter, and not a rival. Alfie learns that Peter has sold the boat, and he and Dandy Mac have to sign on as crew on another trawler. Yopper, who suffered from seasickness, finds a job at a fishmongers. Mickey decides to leave North Shields for Galloway, and Karen, meeting Mickey as she walks to the railway station, decides to go with him.