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Despite the efforts of detective Paul Drake (William Hopper) to protect a secret desalinization process developed by Tryon Labs, the formula is pirated by a rival company. Working undercover for Tryon's head man Dr. Malcolm Scranton (Gilbert Green), Horace Lehigh (Bryan O'Byrne) is on the verge of revealing the identity of the person responsible for the security leak when he is drowned in a chemical vat. Perry Mason (Raymond Burr) ends up defending Dr. Todd Meade (Grant Williams), who apparently had both motive and opportunity to murder Lehigh.