There’s something in the water at Lewgate Docks. Something strange, and green, and deadly. Summoned to the North of England by a mystery informer, the Brigadier finds his investigations hampered at every turn by the local police. Just what are they trying to hide?

While the Doctor uncovers sinister goings-on in the city morgue, Liz attracts the attention of something unearthly. But with Time running out, quite literally, the Doctor, Liz and UNIT aren’t the only ones to find themselves targeted by a world-shattering alien menace...

...because they’ve got a previous Doctor and his best friend Jamie in their sights, too!