| Director | Peter Graham Scott, Seymour Friedman |
|---|
An American, Steve Rossi, enters Britain by slipping past immigration at Heathrow Airport, leading to a national manhunt by the police led by Scotland Yard. Rossi heads into London where he tracks down Bailey, a barman, and asks him about Michael Grand. The barman passes him a note with an address which leads him to a woman, who says she does not know Grand. She agrees to change Rossi's US currency and buy him a coat while he waits in her flat. For money, she gives him another address: Kingston House, a swanky block of flats on Kingston Road. He takes a taxi there and meets Joan Miller who acknowledges it is Grand's flat, saying she is his secretary and he is not there. She claims that Grand is not going to return, but calls Grand who agrees to meet. Rossi wants to stay put in Grand's flat but Joan pulls a gun on him and together they drive to an old terraced house where Wilkes starts quizzing Rossi. Rossi says that Grand offered him a job, working on aircraft design. Joan is asked to accommodate Rossi in her own flat.
Meanwhile the police post Rossi's picture in all the newspapers and quiz various underworld figures to try to locate him. The taxi driver recognises the picture. Joan Miller is revealed to be an MI5 agent. Rossi reveals himself to be an FBI agent posing as a nuclear scientist in an attempt to infiltrate a gang kidnapping western scientists and taking them across the Iron Curtain. Grand has recently arranged the kidnap of an American. With MI5's assistance, Rossi monitors Grand and arranges a meeting with him. Growing increasingly suspicious of Rossi, Grand and his organisation make several attempts to kill him.
Rossi and Joan follow Grand's assistant Irma Brookes, in an attempt to find him. Brookes and a body with some of Grand's ID is found in a burned-out car. Rossi is caught and taken to Hammersmith Police Station. It is explained that Rossi wanted to get into the papers so that Grand would be aware of his presence. Rossi cannot identify the body in the mortuary as Grand as he is unsure of his appearance.
Grand is finally revealed when Max, another taxi driver, informs him of what he has seen both at the burning car and near the mortuary. Rossi dons a naval uniform and tails Grand on foot through empty streets in the city, leaving a chalk trail of markers for Joan to follow. Grand goes to the River Thames where the low tide allows him to walk along the edge. They end up at the Old Swan Pier near London Bridge. Grand pulls a gun and a scuffle begins. Grand escapes to a rooftop of a grain elevator close to The Monument. They end up fighting on an external freight lift heading back to the ground. Rossi wins and the police arrive.