As in several of her other cases, Miss Silver is approached by a person who wishes her help. The next thing she knows the person's murder is headlined in the paper.

This is a not too shabby locked room mystery. The locked room is a windowless annex to a country club (once the murderee's private home). It has one door for which there are only two keys, one in the possession of the owner, the other in the hands of his secretary. The approach to the annex is along a glassed in corridor that is lighted at night so that any person using that route may be seen.

Yet one day Lewis Brading is found dead in the annex and it seems that only one man could have murdered him. However Miss Silver is there to make sure that the guilty and not the innocent suffer.