A wounded British mercenary dies trying to get into the U.S. Embassy in Paris. In his possession is a newspaper clipping with a picture of French ballet dancer Danielle Chabrol. She is engaged in a May-Demcember romance with retired (and widowed) U.S. diplomat Eric Reverson. Erskine and Colby take up the investigation in Hawaii, where Reverson lives. It turns out that Reverson's neighbor, Jim Kellogg, is running an espionage operation and Danielle is supposed to gain access to information and programs Reverson was involved with at the U.S. State Department. Complicating matters is Glen Reverson, the diplomat's grown son, who knows Danielle and who also has feelings for her. Kellogg is more than willing to kill the younger Reverson if he feels Glen is threatening the operation.
—Bill Koenig