Warner Oland returns as Charlie Chan for another round of whodunits. Considered by many to be the best of the Chan films, "Charlie Chan at the Opera" (1936) has Charlie and Lee Chan (Keye Luke) looking into the murder of a diva and finding the prime suspect is her ex-asylum inmate husband (Boris Karloff). Charlotte Henry co-stars. Then, the death of a prominent horse breeder looks like a work-related accident, but Chan's investigation leads to a connection to a gambling ring, in "Charlie Chan at the Race Track" (1936). Luke also stars. The Asian gumshoe must sift through a wild list of suspects when a murder occurs under the big top, in "Charlie Chan at the Circus" (1936). And, working for the U.S. Navy, Chan heads to Berlin, where he clashes with a local policeman while trying to rescue #1 son Lee from a cadre of international spies, in "Charlie Chan at the Olympics" (1937). With Luke, Fredrick Vogeding. 4 2/3 hrs. total on four discs. Standard; Soundtrack: English Dolby Digital mono; featurettes; theatrical trailers.