His name is Kaleidoscope. He claims to have travelled halfway across the universe to warn all humankind that it stands on the brink of extinction. And a certain tenacious young journalist has got an exclusive interview with this alien messiah...

But it’s not Sarah Jane Smith who’s got the out-of-this-world scoop - it’s her rival, the unscrupulous Jenny Nettles. Sarah's busy helping the Doctor and UNIT work out if Kaleidoscope is for real or a fake when RAF Phantoms scramble to intercept an unidentified something homing in on a top-secret missile base.

It seems like Kaleidoscope’s apocalyptic predictions might all be about to come true.