This is a missing episode, an all too common occurrence in the long history of The Shadow radio series. The following plot summary is taken from the excellent and massive tome "The Shadow: The History and Mystery of the Radio Program, 1930 - 1954" by Martin Grams, Jr..
"Relieved of his job as chief chemist of the Brullick Company, Mitchell Hardis develops a drug that cause one to speedily age until death by what appears to be natural causes."
The antagonist is intent on conquering the world and with his cousin intend to eliminate the only person who can stop them... The Shadow. They kill prominent persons and leave clews only our hero can pick up on. This leads Lamont to visit Hardis and, shocker, he drinks coffee laced with the drug. Margot gets an aged Lamont to a hospital and placed in a freezing chamber to inhibit the effects of the drug. Margot is confronted by Hardis and given the usual choice... death by violence of by this weeks clever death device, in this case the aging drug. The Shadow arrives and spoils the dastardly scheme and, realizing the jig is up, Hardis takes his own medicine. How did Lamont come out of this sure fire death sentence? Apparently the drug needs body heat to work and when he was placed in the freezer the drug simply evaporated and youth was restored.
This sounds so far fetched that it probably needs to be heard to be believed.