A fancy dress ball is in full swing when in the tumult of the revelry, Sir Ralph Feltham is found dead...

The British Secret Service agents, working to uncover a large-scale blackmail ring and catch its mysterious mastermind, "The Spider," find themselves at the country residence, Feltham Abbey, where the ball is in full swing.

When Sir Ralph Feltham is found dead, Tony, a bewildered young lawyer, sets out to make sense of the night's activities and the motives of the other guests. Among them is Hilary, an independently minded socialite still in her costume of vivid silk pyjamas and accompanying teddy bear...