OK, maybe grabbing an Atlatean priest from the distant past isn’t a good idea…even if he does for some reason speak English.
Yes, he speaks English, and he doesn’t want to help the Master bring Kronos to the solid world because that would be bad. The Master insists he can control the time-eater and even brings it through. It’s…some kind of guy in a flapping bird suit or something. I think it eats the Newton Institute’s head guy because it goes to him and we don’t see that guy anymore. At any rate, the Master traps it in a room and then sends it back to the time between time, and that almost gets Krasis on his side. Or at least agreeing the Master deserves to be called the Master. Too bad he can’t quite control Kronos yet because the rest of the crystal is still in ancient Atlantis.
But the Doctor knows something is going on. His first clue is when Benton slips away to tell him where the Master is. That one is obvious. Then second is when Stuart reverts back to his normal age. Plus, the Brigadier, Benton, and Dr. Ruth run away in slow motion. That was hilariously bad special effects in that it was literally some actors moving more slowly than others. As such, the Doctor reconvenes in Stuart’s room and builds a device out of odds and ends that can somehow block the TOMTIT until Captain Yates shows up with the Doctor’s TARDIS since that would have finer equipment in it.
But things are never that simple. The Master sees Yates coming on his wristwatch and starts bringing in resistance to stop Yates. First is a knight that drives the car caravan off the road rather hit the guy on the horse. Then there were the roundheads who have muskets and a canon.
What’s a roundhead? I’m not sure. But they have a canon. Always take the people with a canon seriously.
Fortunately, neither side seems able to hit the other until Yates tosses a grenade. The roundheads disappear before the grenade goes off. Typical. By then, the Doctor, Jo, and the Brigadier are on their way to help, with the Doctor and Jo taking the surprisingly fast Bessie for a bit of light comedy. But there’s a plane overhead, a German bomber looking to drop its payload onto Yates and Co. So, the last thing we see as the Master and Krasis presumably get ready to head to ancient Atlantis is an explosion down the road that may have been Yates and the TARDIS.
But I kinda doubt it.