A song holds the key to murder in this Dr. Hugh Westlake mystery from the Edgar Award–winning author who wrote the Peter Duluth series as Patrick Quentin. Patrick Quentin, best known for the Peter Duluth puzzle mysteries, also penned outstanding detective novels from the 1930s through the 1960s under other pseudonyms, including Q. Patrick and Jonathan Stagge. Anthony Boucher wrote: "Quentin is particularly noted for the enviable polish and grace which make him one of the leading American fabricants of the murderous comedy of manners; but this surface smoothness conceals intricate and meticulous plot construction as faultless as that of Agatha Christie." The affluent Bray family was known for throwing the most enjoyable picnics, and this one seemed to be no different to Dr. Hugh Westlake and his precocious progeny, Dawn. When their host's daughter breaks into a version of the old English folk ballad, "Green Grow the Rushes, O," no one gives it a second thought. Little do they know the song portends death. It begins with the bodies of twin boys found in the river, which connects to a lyric from the ballad. And before anyone can even recover from such a horror, more killings occur—all diabolically tied to the song. With help from Dawn and his old friend, Inspector Cobb, Westlake must sort through an ever-shrinking circle of suspects and stop a murderer from striking another deadly note.