A number of top-level racketeers are murdered, each one with a different, unusual weapon. The Green Hornet is contacted about a known list of targets, but before any more information is divulged, his racketeering informant is also killed. The Green Hornet realizes that the key to this mystery is in that list. With his aid Kato, he sets out to discover where it originated and soon finds himself investigating the elite Explorers Club. It quickly becomes obvious that a group of criminals meeting there are the ones behind the murders; and furthermore, that they intend to make the Green Hornet their next target.