This reminded me very much of the Peter Cushing film "Dr. Who and the Daleks" (1965) as the TARDIS deposits the eponymous, but presently comatose, Time Lord (Jon Pertwee) and his assistant "Jo" (Katy Manning) onto the jungle planet of "Spirodon". Fortunately, he manages to recover and together they explore the foliage - complete with some menacing plants that spit a toxic gunge at anyone passing by - and meet up with the crew of a wrecked spaceship who are aware that the natives of this world have the ability to stay invisible. That's the least of their troubles though when they discover that their metallic arch enemy have also become aware of this skill, no longer need metal on which to move and have arrived in great numbers to equip themselves with the ultimate weapon for conquering the galaxy and exterminating everything in sight. It's going to be dangerous, but with the help of their new friend "Taron" (Bernard Horsfall) might they be able to thwart this most cunning of plans before the "Dalek Supreme" arrives? This might have worked better as a four parter, six parts does stretch it just a bit too thin, but once it gets going and there's a good old fashioned battle of wits then it's enjoyable enough for a drama that's largely studio-bound. Not really one of the more memorable adventures this one, but still worth a watch.