Like the first entry in Columbia's "Ellery Queen" series, Ellery Queen's Penthouse Mystery depicts its amateur-criminologist hero as an oafish ignoramus. This time around, Chinese ventriloquist Gordon Cobb (Noel Madison), is murdered by a gang of jewel thieves. Baffled by the contradictory clues, Inspector Queen (Charles Grapewin) asks his son Ellery (Ralph Bellamy) to help out.