Pioneering in both subject and execution, The Mysteries of Myra aimed to avoid the hackneyed melodramatic lines of many early serials. By offering an entirely different theme, the picture purportedly would demonstrate the way that science had become powerful enough to “prove” the existence of the unscientific. The scenario was written by Charles W. Goddard, a veteran of serial pictures who had scripted The Perils of Pauline (1914) and whose association with the Whartons dated back to their first Elaine serial production. On the Myra scripts, Goddard collaborated closely with Hereward Carrington, the well-known British-born American investigator of psychic phenomena and author of more than a hundred books and pamphlets on subjects ranging from parapsychology, spiritualism, and psychic phenomena to stage magic, alternative medicine, and fasting.

Alden, though, recovers and continues to subvert the plans of the Master, whose magical hold over Myra remains strong. The Master “absorbs” Myra’s astral body into his own, unleashes a deadly flood, attempts to incinerate Myra, invokes a chant that causes her heart to fail, and places her in a state of suspended animation. When that fails, he summons a “Fire-Elemental” to set ablaze the barge where Myra is hiding and burn her alive. He then conspires with an elderly couple, promising them an elixir of youth if they agree to destroy Myra. Most dangerous of all, though, is the “Thought Monster” that he creates and sets upon the hapless heroine. But when the Monster overhears the Master’s plan to destroy it once its deadly work is done, it turns on the villain and deals him a final and fatal blow, ensuring that Myra and Alden are at last free of him—and, presumably, free to live happily ever afterward.

A production as nontraditional as Myra demanded a vigorous and nontraditional promotion. And that is precisely what Hearst delivered. He peppered his many publications with graphic and colorful ads for the serial. Later novelized by author and director Eustace Hale Ball, the serial also enjoyed various promotional novelty items, from small metal advertising buttons to cardboard masks (now highly collectible). Another popular giveaway was the “Crolette,” a cardboard planchette that purportedly could be manipulated in order to contact the spirit world, much like a mini-Ouija board.