Delaney's holiday on the idyllic Caribbean island is rudely interrupted when he finds it is in the direct path of Hurricane Hilda - and there is only one small plane to fly everyone out.

Delaney has reasons to believe the saying "Diamonds Sing Louder Than Nightingales" when Garnett sends him to Teheran to investigate the disappearance of some valuable packages of gems from the registered mail.

Delaney, on a visit to South America, finds himself involved in the aftermath of a small revolution.