Kicked out of his father's house and on the run from the cops, homeless young Nick runs into Joe's fish shop in New Jersey. Although Joe initially wants nothing to do with Nick, his wife Betty convinces him otherwise. They take him home and Betty offers Nick the job of Joe's helper because Joe has a weak heart. She also gives Nick her adult son Danny's bedroom to stay. She sees Nick as a member of the family. Danny has gone to Hollywood to make it big as a comedian. He sends home video tapes of him performing his unfunny routines. Betty doesn't mind his arrogance.
Joe teaches Nick how to be a fish man. Nick is mistaken for Joe's son. Joe loves the fish business so much he vows not to sell to the condominium developers who are buying out the surrounding businesses for millions of dollars. Betty hates the job and is furious at Joe for turning down the developers. She asks Nick to talk to him. He does, and Joe sells the business.
Even though Nick keeps telling himself to leave, he begins an affair with grateful Betty. Danny comes home with his new wife Amy and baby with new plans to make it big in New York. Danny becomes jealous of Nick because he knows about Nick's affair with Betty, and because Joe plans to start a charter boat business in Florida with Nick's help. Danny also suspects Nick of having an affair with Amy.
Since Danny has no work, Betty gives Danny some money from the sale of the business without telling Joe. Danny hints about her affair with Nick and she is angry. Later, as she, Nick, Danny and Amy are seated at a table, Betty thinks she is caressing Nick's foot at her crotch. But it turns out to be Danny's foot. She is angry and horrified, but increasingly unhinged Danny gloats.
Betty asks Nick to run away with her by taking a cruise to Mexico. While delivering fish to Danny's wife Amy, Nick learns Danny beat her. Nick sends Amy and the baby out of town.
When Danny finds out Amy has left, he phones Joe and accuses Nick of running away with Amy, stealing the money from the sale of the business and stealing Betty. Betty confesses she gave the money to Joe but she and Nick also confess to the affair. Joe attacks Nick but dies from a heart attack. Nick regrets betraying Joe. On the pier, Nick doesn't resist as Danny slashes his throat. Betty is dressed in an evening gown, presumably on her cruise to Mexico.