At the time that Ted Patrick is planning to pull off his biggest house-breaking job, Dr. Morelle, aided as ever by Miss Frayle, sets up an off-beat criminological experiment, which is destined to have unexpected results.The success of Ted Patrick?s coup, achieved with the inside help of a pretty blonde, Myra Campbell, is marred by the killing of a village policeman. Patrick gets away with the loot but runs into trouble when his cleverly planned alibi crumbles dramatically. In a last desperate effort to keep himself in the clear, he deliberately becomes involved in Dr. Morelle?s strange scheme.At first it seems that Ted Patrick?s luck will hold, but he reckons without Dr. Morelle . . . and without Myra Campbell herself!