A London solicitor, Mr. Renfield (Dwight Frye), is dispatched to a remote castle in Transylvania to finalize the move of Count Dracula (Bela Lugosi) to England. Dracula enslaves Renfield and reduces him to a gibbering, fly-eating lunatic. The Count takes up residence in the abandoned Carfax Abbey, next door to Dr. Seward's sanitarium where Renfield has been committed.
The Count first vampirizes family friend Lucy (Frances Dade) then sets his sights on Seward's daughter Mina (Helen Chandler). She slowly falls under the Count's power and is nearly vamped herself until interference arrives in the form of wise old Dr. Van Helsing (Edward Van Sloan).
The climax comes when Van Helsing and Mina's finance John Harker (David Manners) follow Renfield to the Count's subterranean lair just before sunup. Thinking Renfield has betrayed him, the Count kills Renfield but cannot keep the heroic duo from staking him as the sun rises. The Count is dead and Mina is freed (Van Helsing presumably stakes Lucy off-screen).