Well, Leela is on her way to getting steamed. Someone should do something about it without alerting the Collector or Hade or other officious idiots.
That last part is important because the radio to alert the Doctor his time is up would open a channel to the entire steam room, and Mandrel uses it anyway. Granted, the Doctor does free Leela in time, and Mandrel and the others have stopped the fear gas from going everywhere, so it’s time for a good, old fashioned uprising.
That’s good for the human race, but not so much for the Collector.
But now the Doctor has a plan. He just needs to get to the master control room before the Collector does, and Leela was there already, so she can take him back there. They do get there and the Doctor only has to hypnotize one guard before Leela stabs him. Yes, he hypnotizes her too. That always happens. But, since Leela knows the room, he’s able to rewire a control panel, open a hidden safe, and generally make things harrier.
Where’s K9? Assisting the rebels. Apparently, the K9 machine broke down quite a bit, so he probably only gets limited stuff to do as a result.
And sure enough, the Collector comes back at about the same time the workers are enjoying quality rooftop time where they toss Hade off one. Maybe that goofy hat he wears has some strong cushions in it.
But the Doctor knows the Collector is running a company, so why not pretend to be an investor? That actually works as it allows him to learn the Collector’s plan. It seems the humans ruined the Earth and asked for help. The Collector isn’t human. He’s a Usurian, a race of sentient mold. He only took human form to work with humans. His people gave Earth a loan to move them to Mars, and they’ve been working for his people ever since. When they used up Mars, they skipped the gas giants and went to Pluto. And since that planet may be used up soon, well, the Collector is going to abandon everyone and leave them to die.
Yeah, he sucks.
By then, even the guard who overheard ain’t cool with this guy anymore, the rebels are winning, and the Doctor managed to bankrupt the Collector before the guy got back. The Collector is so shocked, he reverts to his natural form and gets sucked down a hole into a compartment beneath his wheelchair. And then the Doctor just plugs the hole.
So, problem solved. The humans can return to Earth now that its resources have apparently renewed themselves, but the Doctor and his companions are free to move on to wherever is next. And the Doctor even manages to find a way to beat K9 in that chess game they were playing in Part 1.
It involves tilting the TARDIS and knocking over the board.
Well, that wasn’t very mature of him.