In the movie studio in Hollywood where Sherlock Holmes's The Valley of Fear is being filmed, comedian-cum-amateur sleuth Groucho Marx and his writer, Frank Denby, stumble across a stage set for death. The body of the German emigre director Felix Denker has been found in Holmes' favorite armchair, stabbed in the chest with the famous detective's pearl-handled letter opener.

Miles Ravenshaw, the actor portraying the immortal sleuth in the movie and a former member of Scotland Yard ridicules Groucho, calling him "a slipshod gumshoe," and challenging him to a race to find the killer. As always, Groucho rises to the occasion, and with his version of the familiar words "the games afoot again, Rollo," enlists his faithful sidekick in the investigation.

The race is on across Hollywood and its surrounding venues as the two desperately search for the solution --but not without having a lot of fun along the way. Full of the quipping comic's wisecracks, the stars, the glitz and the glamour of the Hollywood of the 1930s, the third installment in Goulart's highly-praised mystery series is a must-have for all Groucho fans.