Matt Helm is called out of retirement to stop the evil Big O organization who plan to explode an atomic bomb over Alamagordo, NM, and start WW III.

Dr. Matthew Clark is the head of a state institution for intellectually disabled children. Jean Hansen, a former music teacher anxious to give her life some meaning, joins the staff of the hospital. Jean, who tries to shelter the children with her love, suspiciously regards Dr. Clark's stern training methods. She becomes emotionally involved with 12-year-old Reuben Widdicombe, who has been abandoned by his divorced parents.