"That's an Apan warstinger," said the tall chap. "Running a little earlier than we thought." He turned to face Greh and his grin had a new, startling grimness. "I think we'd better be getting back to the TARDIS, don't you?"
The Apan Hive considers itself a civilised culture, but even the civilised get hungry: when someone has the Food there is no choice but to take it from them. Unluckily for the planet Verdant, the galaxy's third-largest natural source for unrefined hydromel, that ravenous appetite has just arrived in orbit looking for take away.
Well that's one take on the situation. Naturally the Doctor suspects something else is behind the invasion and it doesn't take long for him to be proven correct. A shadowy corporation hunts for somebody who isn't in his right mind, old friends and enemies are shuffled around the board by a transdimensional mastermind, and an insidious bioweapon that quite literally changes the face of warfare waits to be released.
And the only person who is who he claims to be is starting to find it all a soul crushing bore.