When a man dies after falling from the top floor of a multi-storey car park, the Doctor and Jo wonder why it should be of interest to UNIT. Then they see the protuberances on the man's back... As he fell, he tried to grow wings.
Looking into the man's past leads the Doctor and Jo to a remote private hospital where the staff aren't as helpful as they could be, and the Chief Administrator is unavailable to meet with them.
Breaking into some restricted wards, the Doctor notes the presence of alien and futuristic technology. The whole thing bears the unmistakable hallmarks of one of his own people's interference, one of his old foes. Except not perhaps the one he might have imagined.
The Monk is back. And this time his meddling may have gone too far.
The Doctor and Jo land on Port Anvil – a bleak, abandoned mining colony on the remote planet Burnt Salt. A huge armoured crate has recently arrived in the almost derelict Spacehub. No-one knows who it's for. No-one knows what it contains.
Strange creatures lurk around the outskirts, and a rag-tag population of misfits inhabit what is left of the town: a saloon bar owner, a literal one-man band and a hunter of very unusual prey. If they want to survive the night, they're going to have to work together.
Because the Cybermen want the contents of the crate. And they will stop at nothing to get hold of it.