Desperate Measures

What do you do when you return home and find a dead body on your bed? You don't know the person and it wasn't there when you left home. You call the police, of course. More to the point, when they arrive, the body has disappeared and there's no sign of anything wrong...  Two ordinary people, out for an evening's entertainment are helplessly plunged into an adventure involving murder, secret papers, stolen jewellery, kidnapping, and a car chase through the streets of London.