Paul and Steve are called upon to crack a case involving Carl Milbourne, the brother-in-law of wealthy financier Maurice Lonsdale. After the news that Carl has perished in a fatal car accident, rumours begin to stir that despite all odds, Carl is alive and well.
When Maurice's widowed Sister Margaret pleads for the crime-fighting duos help, Paul and Steve find themselves on a trail of deception stretching from London to Switzerland. Their lives are in grave danger as everything is done in an attempt to stall their search anonymous gunmen, exploding cars, ransom demands, and a mysterious rendezvous that may prove to be the end of Paul and Steve