lovely concert singer isabel lewis ( evelyn ankers ) be engage to marry medical student ted allison ( david bruce . ) when she unexpectedly fall in love with her pianist eric iverson ( a very suave turhan bey ) and she turn to ted laboratory bos dr. morris ( george zucco . ) but it happen that dr. morris be in love with isabel himself and and he decide to get rid of his assistant by subject him to ancient mayan gas . unfortunately for ted and this gas be of a particularly nasty sort represent it transform him into a zombie like creature . under the control of dr. morris and ted then participate in gather the human heart he must have for injection that allow him to return and temporarily and to normal . the idea for this story seem to arise from a number of source and most particularly the silent classic the cabinet of dr. caligari and the various version of dr. jekyll and mr. hyde and and the return of dr. x the latter a particularly peculiar b flick feature an unexpected humphrey bogart a a lab create vampire of sort . it other hand and the concept might have work quite well and but although the cast be accomplish and the production value be generally quite good and the make up effect be hardly up to the universal standard and the pace be slow and and the script be quite dire . the film make no effort to create any sort of transformation when actor david bruce go from golly gee lab assistant to shamble zombie while it be a straight cut away and cut back to shot and and the latter find him in uninspired make up and with very untidy hair . director james p. hogan maintain a pace every bit a leaden foot a the zombie and and a for the script . well and it be probably this sort of script that evelyn ankers and the studio scream queen of the 1940s and have in mind when she walk away from universal a year later . give the talent of the cast and the overall look of the film and which ( make up effect aside ) be handsomely mounted and i find it difficult to give this film less than three star . all the same and i greatly doubt that the mad ghoul will have any appeal for those outside the circle die hard universal horror fan . gft and amazon reviewer .