Meg Elgin, Muriel Pavlow, a woman who has just learned that her husband, a war hero reported missing in action in France, might still be alive, is drawn into a tense chain of events. Engaged to Geoffrey Leavitt, Donald Sinden, she arranges a meeting at a bustling London railway station, accompanied by the police. When a distant figure in an old coat catches her eye, the man being chased is captured, and it turns out to be Duds Morrison, Gerald Harper — a former soldier and recently released convict — who refuses to divulge anything. With no solid charge against him, Morrison is released, leaving Meg and Leavitt with more questions than answers.
Geoffrey Leavitt, Donald Sinden, pursues Morrison in an effort to uncover the truth behind his sudden appearance and masquerade as Meg’s husband. Morrison again refuses to speak and attempts to flee into an alley, but the pursuit takes a brutal turn: a group of street musicians, ex-commandos and Morrison’s former comrades, beat him to death and seize Leavitt as their prisoner.
The street musicians are revealed to be veterans who had served alongside Morrison on a Brittany raid led by Major Elgin, Meg’s husband. They are desperate to locate a treasure they believe Elgin knew about, hidden in a house in Brittany. They also want to find their former fellow fugitive, Jack Havoc (aka Johnny Cash), Tony Wright, who has escaped from prison and is thought to know the treasure’s whereabouts. Their attack on Morrison stems from suspicion that he is Havoc’s accomplice, and they capture Leavitt because they mistake him for Havoc.
For years the musicians have relied on a life as street performers, begging from passersby, but the plan to keep Leavitt captive is a grim one: releasing him could expose them to charges for Morrison’s murder. Their control over Leavitt persists until a beat constable, acting on a CID tip to investigate the squat, rescues him.
Reunited with Meg, Leavitt and the others head for Brittany to locate the rumored treasure, guided by a message left by Major Elgin. Havoc, who has joined his former allies and learned the location, heads to France with the same goal. The revelation changes everything: the so‑called treasure is not money but a priceless work of art—a small Madonna statue whose beauty is described as priceless. A climactic confrontation on the Brittany cliffs brings Havoc into a final confrontation with Leavitt, culminating in intervention by the French police.
