At the Naismith mansion, they've got the Master on a collar and leash, in a straight jacket. They finally light up the giant alien tech, which is clearly not from Earth. When Naismith points out that neither is the Master, the two sketchy scientists stare at each other, and they run off to freak out about him downstairs, releasing the shimmers that make them look human and revealing themselves to be spiky and green and annoying. Verdict: "What if this visitor is some sort of genius? We're hijacking this project, maybe we can use him, too. Harold Saxon, or whatever he is, might be exactly what we need." I guarantee this is not the case, but to be honest I hate the Vinvocci more than I hated the Slitheen, so I could care less.
The Gate was found inside a spaceship, buried at the foot of Mount Snowdon, and taken by Torchwood One and subsequently "acquired" by Naismith, after the whole Void thing. The Master likes the cut of Joshua's jib, but any bonding that might occur as a result is undercut by the Master noting also that he would taste delicious. The Master's turkey is delivered and he pounds the whole thing, which is totally disgusting, and then Naismith explains the Nuclear Bolt. And we're using "explains" rather loosely here: Basically, it's some kind of two-cell plastic unit that houses the power supply of the Gate. Somebody has to monitor the energy feedback 24/7, so it doesn't explode or vent, which means when one door locks the other one unlocks. "The power feeds through to the Gate, where it encourages some sort of cellular regeneration." He shows the Master a lady whose arm used to be burnt and now isn't. Naismith then explains that he wants the Master to fix it up entirely and then they can use it to make his daughter immortal. Apropos of nothing, the little weirdo goes, "Abigail. It means Bringer of Joy." I fuckin' hate the Naismiths.
The TARDIS appears on the estate, and the Master can of course immediately smell him, so he gets to work. Meanwhile, Wilf's mind is blown -- in a good way -- by how they went from a place to a place, and then follows the Doctor out into the building. He sets the TARDIS one second out of sync so the Master can't get his skeleton-hands on her, and they sneak past the Naismith's guards, sonic a tiny door, and then back themselves into it, which is very cute. Meanwhile, the annoying scientists are marveling at the Master's results, like so: "The shatterthreads have harmonized! The fiberlinks have densified! The multiple overshots have triplicated!" The Doctor appears to them, removing their shimmers immediately, and -- while upstairs they lock the Master back up again, to his disappointment -- freaks out on the scientist jerks trying to figure out the Master's new little game he's playing.