context: Baron Victor Frankenstein (Cushing) is housed at an insane asylum where he has been made a surgeon at the asylum, and has a number of privileges, as he holds secret information on Adolf Klauss, the asylum's corrupt and perverted director (John Stratton). The Baron, under the alias of Dr. Carl Victor, uses his position to continue his experiments in the creation of man.
  When Simon Helder (Briant), a young doctor and an admirer of the Baron's work, arrives as an inmate for bodysnatching, the Baron is impressed by Helder's talents and takes him under his wing as an apprentice. Together they work on the design for a new creature. Unbeknown to Simon, however, Frankenstein is acquiring body parts by murdering his patients.
  The Baron's new experiment is the hulking, ape-like Herr Schneider (Prowse), a homicidal inmate whom he has kept alive after a violent suicide attempt and on whom he has grafted the hands of a recently deceased sculptor (Bernard Lee). Since Frankenstein's hands were badly burned in the name of science (possibly in The Evil of Frankenstein or Frankenstein Must Be Destroyed), the shabby stitch-work was done by Sarah (Madeline Smith), a beautiful mute girl who assists the surgeon, and who is nicknamed "Angel". Simon tells the Baron that he is a surgeon, and the problem is solved. The Baron reveals that Sarah is the daughter of the director and has been mute ever since he tried to rape her.
  Soon new eyes and a new brain are given to the creature. When the creature â lumbering, hirsute and dumb â is complete, it becomes bitter and intent on revenge. It ultimately runs mad on a killing spree in the asylum, killing several inmates, including Klauss. Eventually, it is fully overpowered and destroyed by a mob of inmates. Simon is devastated by the loss of life and reports to Frankenstein; however, the Baron feels that it was the best that could happen to such a creature, and is already considering a new experiment with other involuntary donors. The three start tidying up the laboratory whilst Frankenstein ponders who should be first to "Donate"...
question: who enlists helder as an assistant to help in the tending of the medical needs?
answer: Baron