Inviting famed chemist Felix Benet (Lugosi) and other professional colleagues for a meeting, astrophysicist Dr. Janos Rukh (Karloff) plans to unveil his latest scientific discovery.

The big news? Rukh has proven that a huge meteorite crashed in Africa eons ago, and that portions of the meteor contain a mysterious new element called 'Radium X.'

So, he and his associates embark on a quest to Africa in hopes of locating the crash site, but it's Rukh himself who finds the Radium X deposits.

However, when he exposes himself to the properties of the strange element, Rukh turns into a glowing monster whose days are limited...and whose physical touch means instant death to whomever receives it!

As his brain deteriorates - and his jealousies are ignited - the increasingly demented Rukh becomes a mad killer out to assassinate his friends and loved ones.

Great art deco sets and confident direction from Hillyer (who helmed Dracula's Daughter the same year) highlight this sci-fi terror, but of course it's Lugosi and Karloff who really breathe life into The Invisible Ray.

And although Bela is terribly underused here, both legends deliver enthusiastic, watchable performances.

Best scene: that, uh, combustible climax.