The Phantom Creeps is a 12-part serial from 1939 starring Bela Lugosi as Dr. Zorka, a mad scientist with the intent of ruling the world.  12 chapters were produced, the first 3 of which were used on Mystery Science Theater 3000. Installments of this serial were riffed during Season 2 in experiments #203, #205, and #206.
The twelve installments were later edited down into one feature-length film, which became a RiffTrax presentation in 2018.
The evil Dr. Zorka, having discovered the secrets of suspended animation and invisibility, is plotting to rule the world. Zorka has developed a mechanical spider which will destroy whoever holds an electrically charged wafer. He refuses to turn the invention over to the U.S. government and is determined to sell it to whichever country is the highest bidder.
Zorka's former colleague, Dr. Mallory, believes Zorka is guilty of treason. Mallory contacts military intelligence, and agents are sent to question Zorka. To throw the agents off his trail, the mad scientist fakes his death in a car crash using the body of a hitchhiker.
Later, plucky girl reporter Jean Drew (Dorothy Arnold) stows away on the military airplane which is bringing Zorka’s wife to identify the scientist's body. The plane is destroyed by one of Zorka's mechanical spiders, which Zorka had previously planted on his wife.
Dr. Zorka continues to elude the authorities, using his invisibility belt and deadly mechanical spider. Military intelligence agent Bob West (Robert Kent) fights and overcomes Dr. Zorka’s assistant Monk. Bob then pursues an automobile into the hills, believing it is driven by someone who has learned Zorka’s secrets. Jean, the reporter, accompanies Bob as he searches the abandoned car. Bob discovers a strange disk, which the invisible Zorka has planted in the deserted car. Death by mechanical spider seems imminent for Bob and Jean.
Dr. Zorka desperately tries to guard a meteor fragment from which he derives his destructive powers. Dr. Mallory invents the “neometer,” an instrument he believes will detect the presence of Zorka’s meteorite. Government agents Bob West and Jim Daly, armed with the neometer, capture Zorka's assistant Monk while he is trying to escape with a heavy case. While taking Monk to headquarters, Bob attempts to open the insulated case. The case contains the dangerous meteorite fragment, and opening the case unleashes such a destructive force that it demolishes several electrical towers along the roadside, as well as the agents’ car.