Jason falls under the hypnotic spell of two glamorous thieves,Claudia and Elaine. They steal the only copy of his recently completed film script,demanding that,for its return, he poses as an expert in ancient manuscripts in order to steal the Constance Missal,a valuable document recently acquired by the British Museum. He is to authenticate it for one Lord Barnes but his lordship is also planning to obtain the Constance Missal for himself.