This is one of Ed McBain’s earlier work, first known as Murder in the Navy, under his pseudonym Richard Marsten.
A nurse, Claire Cole, was murdered in the radar shack on board the USS. Sykes. The Captain appointed an investigation board, with Lieutenant Chuck Masters, to look into the murder. The FBI sent their agents; arrogant and unfriendly men who were not too pleased about amateur help. Finally, they narrowed the list of suspects to three men, who have recently gone to the hospital, and had a chance to know the dead nurse, namely Perry Daniels, Alfred Jones and Richard Schaefer.
Schaefer remembered having seen the killer with Claire in the hospital.
He confronted the killer one night at the deck, who panicked and threw him overboard. The FBI deduced that Schaefer had committed suicide, having been driven by guilt and fear of exposure. Lt Masters, however, was not convinced and continued the investigation himself. He met Jean Dvovak, the room-mate of Claire, and was attracted to her. Jean told Masters that Claire had gone with a navy man to Wilmington on a weekend, as she had seen a train ticket on Claire’s table.
Meanwhile, the killer had checked himself into the hospital, trying to meet other nurses. He was intensely attracted to Jean, who was attending to him.