Dr. Frank Mannering, played by Patrick Knowles, is a character in the film Frankenstein Meets the Wolf Man.
Dr. Mannering treats Lawrence Talbot, who has a head wound, in a Cardiff hospital. Talbot tries to explain the wound came from his father who killed him with a cane with a silver handle but the full moon brought him back to life as a werewolf. Mannering doesn't believe him until he sees first-hand evidence.
Talbot leaves and seeks out Maleva, who tells him to seek out Dr. Frankenstein, who may be able to help him. Finding that the Monster is unable to locate the notes of the long-dead doctor, Talbot poses as a potential buyer of the Frankenstein estate in order to seek out Baroness Elsa Frankenstein the daughter of Dr. Ludwig Frankenstein, hoping she knows their hiding place. She declines to assist Talbot, but the pair are invited to the "Festival of the New Wine" by the Burgomeister. During the festival, a performance of the life-affirming folk song Faro-la Faro-Li enrages Talbot as Dr. Mannering arrives. The doctor, having followed him across Europe, attempts to persuade Talbot to return to Wales before he has another spell. Talbot refuses to go with Mannering, and the Monster crashes the festival. With the Monster revealed, Elsa and Mannering agree to help the villagers rid themselves of Frankenstein's curse forever. The following morning, the couple, with Maleva in tow, meet with Talbot and the Monster at the ruins. Mannering is instantly fascinated by the Monster from a scientific perspective. The Baroness gives the notes to Talbot and the doctor. Mannering studies the notes and learns how to drain all life from both Talbot and the Monster, believing the laboratory can be repaired for the task.
In the meantime, the villagers are dismayed to see crates of scientific instruments arriving for Dr. Mannering. Ignorant of Mannering's plan to cure Talbot, the villagers fear another return of the Frankenstein Monster, and they grow suspicious. Vazec, the innkeeper, details a plan to destroy the dam overlooking the Frankenstein estate with dynamite and drown all within, in the hopes that this will put a final end to the attacks from both the Frankenstein Monster and the Wolf Man. The Burgomeister dismisses the idea as nothing but a drunken notion, but Vazec is determined and puts his plan into action.
Meanwhile, Dr. Mannering begins his experimental procedure of using electricity to drain the life force from both Talbot and the Monster, but Mannering's scientific curiosity to see the monster at full strength overwhelms his logic, and to Elsa's horror, he decides to alter the machines to fully revive the monster. The experiment coincides on the night of a full moon, and Talbot transforms yet again as the Monster regains his strength (and eyesight); both escape their restraints. The Monster begins to carry Elsa away, but the Wolf Man attacks him, and she escapes from the castle with Mannering. The Wolf Man and the Monster then engage in a fight until they are both swept away in the flood that results when Vazec dynamites the dam.