While John and Kirstie Raven are in Paris they come across an old college friend of Kirstie's, Kirk Cameron. Learning he is coming to London in an attempt to raise some funds, Kirstie insists he stay with them on their houseboat in Chelsea. What Cameron doesn't tell his hosts is that he has agreed to help a casual acquaintance in a little 'industrial espionage': and what Cameron hasn't been told is that he is to be involved in robbing a safety deposit box . . .