After seeing the animated first part (the original broadcast is no longer available), Episode 2 of The Invasion is kind of shocking: for one thing, the live-action footage doesn't always look good (if people are willing to spend time and money restoring classic films for DVD reissues, why not do the same thing with TV shows?); secondly, the opening chapter was sort of slowed down by the not-so-state-of-the-art animation, while this follow-up is astonishingly slow on its own.
Expanding on the closing "cliffhanger" of Ep. 1, we learn that the mysterious Tobias Vaughn possesses an extraterrestrial device (which looks quite shoddy, courtesy of the low budget), confirming the Doctor's suspicions. Unfortunately, he isn't aware of this, as he and Jamie have left the building to continue their quest for the missing Professor Watkins. Zoe, on the other hand, is having lots of fun with Watkins' niece Isobel (much better in the flesh), although she soon gets tired and decides to look for her friends.
It is this whole "everyone looking for everyone" gimmick that annoyed me the most: although intriguing at first, it very quickly becomes repetitive, a notion that's made even sadder by the absence of relevant plot points (the title sequence is more exciting than the story). The series' trademark humor is also inexplicably gone, save for a brief, acceptably entertaining reunion between the Doctor and former General (currently Brigadier) Gordon Alistair Lethbridge Stewart (Nicholas Courtney), which also has the function of introducing UNIT (United Nations Intelligence Taskforce) to the show. Apart from that, though, The Invasion: Episode 2 has very little to offer.