the third collaboration for karloff and lugosi see a move away from poe and into the realm of the science fiction serial . karloff play dr. janos rukh and creator of a device that can capture light ray through his telescope in the carpathian mountain and translate them into picture that form a visual history of the universe . before several guest and include lugosi a dr. benet and an astro chemist who have previously scoff at rukh theory and he demonstrate the existence of an unknown radioactive element and here term radium x and contain in a meteor that fell to earth in darkest africa several thousand year ago . karloff join the expedition to prove his theory and but radium x be a tricky compound it level mountain at long range and and cure blindness at short range . rukh be careless and however and and poison himself and glow in the dark rather like those old ready breck commercial . dr. benet be on hand to devise a counter active for the radiation and but combination of poison and cure drive rukh insanely paranoid . convince he have be cheat and he seek out the member of the expedition in paris and include his estranged wife and and his very touch while in his radioactive state mean death . along the way we get the old pseudo scientific idea that a dead person eye record the image of their killer ( a remarkably distinct karloff . ) and the radium x device use to symbolically melt statue that represent the expedition member . and even a touch of james whale in a cockney landlady in paris . the invisible ray be great fun and aside from the gothic opening it interest to see universal move the action around to africa and paris . the film lack pace and but be always absorb . karloff slightly overdo his performance but lugosi be terrific . universal use the basic story outline again in man make monster and this time with lon chaney jr. a the glow menace ( this time cause by electricity ) and lionel atwill a a much madder doctor than lugosi be here . the invisible ray be a sombre and clever little film with much to admire . not as famous a other universal horror and perhaps and but it work and be highly entertaining .