Ronnie's party is going well, but his mother Alice is waiting for her husband Tom to return from the office to help supervise. The doorbell rings, but instead of Tom it's Simon Potter, a strange little boy who Ronnie dislikes, and who knows some unusual and horrifying variations of children's party...
A man and a woman are poisoned. The woman dies, but the man survives. The finger of blame begins to point at the man. A policeman and a newspaper journalist pursue the truth.
