Dr. Wilfred Glendon was a wealthy and world-renowned English botanist who journeyed to Tibet in 1935 in search of the elusive mariphasa plant. While there, he was attacked and bitten by a creature later revealed to be a werewolf, although he did succeed in acquiring a specimen of the mariphasa. Once back home in London he was approached by a fellow botanist Dr. Yogami, who claimed to have met him in Tibet while also seeking the mariphasa. Yogami warned Glendon that the bite of a werewolf would cause him to become a werewolf as well, adding that the mariphasa was a temporary antidote for the disease.
Glendon did not believe the mysterious Yogami. That is, not until he began to experience the first pangs of lycanthropy, first when his hand grew fur beneath the rays of his moon lamp (which he was using in an effort to entice the mariphasa to bloom), and later that night during the first full moon. The first time, Glendon was able to use a blossum from the mariphasa to stop his transformation. His wife Lisa Glendon was away at his aunt Ettie Coombes' party with her friend Paul Ames, allowing the swiftly-transforming Glendon to make his way unhindered to his at-home laboratory, in the hopes of acquiring the mariphasa's flowers in the hopes of quelling his lycanthropy a second time. Unfortunately Dr. Yogami, who was also a werewolf (specifically the one who'd bitten Glendon in Tibet) had snuck into the lab ahead of his rival and stolen the only two blossums. As the third had not bloomed, Glendon was out of luck.
Driven by an instinctive desire to hunt and kill, donned his hat and coat and ventured out into the dark city, killing an innocent girl. Burdened by remorse, Glendon began neglecting his wife Lisa (more so than usual), and made numerous futile attempts to lock himself up far and away from home, including renting a room far from home at the inn of Mrs. Whack and Mrs. Moncaster, but whenever he transformed into the werewolf he would always just escape and kill again. After a time, the third blossum of the mariphasa finally bloomed, but much to Glendon's horror, that too was stolen by Yogami. After turning into the werewolf yet again and slaying Yogami, Glendon went into the house in search of Lisa, for the werewolf instinctively sought to destroy that which it loved the most (and despite being a workaholic who was hardly around, Glendon really did love Lisa).
After jumping Paul Ames (but not killing him), Glendon cornered Lisa on the staircase and was about to move in for the kill her when Paul's uncle, Colonel Forsythe of Scotland Yard, arrived with several police officers in tow. He shot Glendon once, killing the werewolf of London. As he lay dying, Glendon apologized to his wife and thanked Colonel Forsythe for the merciful bullet. He then perished, reverting to his human form in death.
Glendon, whose first name has been changed slightly to Wilfrid, has a much different fate in the novelization of Werewolf of London. Rather than battle Yogami to the death and then be killed by Forsythe, Glendon cooperates with Yogami and the pair see a hypnotist who they hope can help them stave off their transformations long enough to ride out the full moon without killing anyone. After this, they plan to go to Tibet together and collect more Mariphasa plants. However it does not go as planned. They both become wolfmen, and Yogami kills the hypnotist, and Glendon then kills Yogami. The novel ends with Glendon alive but contemplating suicide using the hypnotist's gun.