The Doctor’s companion Jo Grant, who was concussed when she jumped out of Bessie in Part 3, wakes up in her bedroom at the Cloven Hoof pub during the latest earth tremor that signals the appearance of the Daemon. Before the local doctor sedated her, she was insistent on going to the cavern under the church in search of the Master. Now that she’s conscious again, it’s the first thing on her mind.
Her UNIT friends, Sergeant Benton and Mike Yates, along with Miss Hawthorne, are right at the foot of the stairs, blocking her exit. So Jo sneaks out instead, climbing out of her window, walking across a flat part of the roof, and finding a handy ladder to get down so she doesn’t have to make another dangerous jump.
I thought for a moment that she was intending to hijack Bessie, parked nearby, but she only slips around the car on her way to the church.
The Doctor, meanwhile, is still at the barrier that encircles the village of Devil’s End and prevents anyone from getting in or out by incinerating them. He’s advising the UNIT technical team on the other side of barrier about how to generate sufficient electrical power to supply the oscillator he described in the previous episode so they can create an opening in the barrier big enough to drive their van through.
How to do it? “Reverse the polarity!”
You knew he was going to say that sooner or later