While Part 1 had a good set-up, with a stormy night, an archeological dig into an ancient longbarrow burial mound with the ominous name of the Devil’s Hump, and a Black Mass calling up something evil, but this second episode is where the daemons of the title really start to get out and around. 
Part 2 begins just where the first part ended; Mr. Magister (aka the Master), having successfully summoned up a certain powerful being, is shouting “Azael! Azael!” His cowering coven notice that the stone gargoyle in the corner of the cavern now has glowing red eyes.
Back at UNIT HQ, Mike Yates and Sergeant Benton are watching a rugby game on the office telly and realize they’ve missed the midnight archeology program about the opening of the Devil’s Hump longbarrow–which the Doctor had wanted to prevent. They switch channels to try to catch the end of the show, and the first thing they see is Jo sobbing over the supine and frosty form of the Doctor. The transmission breaks off.
The two men first attempt to contact the Brigadier, who’s out for the evening dining in his dress uniform. When they can’t get hold of him, they decide to head for the village of Devil’s End themselves.
The Doctor has been frozen by the blast of snow and icy wind that emerged from the Devil’s Hump barrow once Professor Horner opened it. I assume the professor was killed by the same blast, since we never hear another word about him. Other people who were a little bit farther from the opening seem to have survived.
The village doctor gently tells the sobbing Jo that her Doctor is indeed dead–but before he can turn into Tom Baker ahead of schedule, a faint pulse is detected. The small-d doctor is confused by what sounds like two heartbeats in his patient’s chest, but he has the Doctor conveyed to a bed in one of the rooms at the Cloven Hoof to be thawed out.
The television news team at the barrow site swiftly pack up their gear, eager to get away. After they depart, we see a pair of larger red eyes glowing in the dark from within the barrow.
In the morning, even though his coven has gone, the Master is still down in the cavern below the church quietly praying. I take it that his duties as parish vicar don’t require him to do any morning services up in the church. As if in response to his prayers, some very large creature we don’t see comes stomping out; it casts its shadow over the hapless constable, who was sitting on guard at the gate of the barrow field.
Mike and Benton have taken the Brigadier’s helicopter to fly to Devil’s End as swiftly as possible. As they approach the village, they see from the air what looks like a line of enormous cloven hoofprints across the countryside from the barrow toward Devil’s End. Benton estimates that the creature that made them must be at least 30 feet tall.
When they finally land on the village green and enter the Cloven Hoof, it’s pointed out by a close-up that the Devil’s Foot on the pub sign is pretty much exactly the type of giant hoof that could make those enormous footprints.
Inside the pub, Yates and Benton are relieved to learn that the Doctor’s going to be all right, even though Jo informs them that things in Devil’s End are “really bad, you know… Devilish!”
While making a quick reccy around the village, Benton hears Miss Hawthorne shouting for help. He discovers her shut up in the cope chest in the church vestibule, where one of the Master’s minions, the church verger, put her last night to keep her from interfering. Miss Hawthorne dubs her rescuer a “parfit, gentil knight” and a sort of romance develops between them, at least as far as she’s concerned. Benton seems bemused by her attentions.
The two of them have to hide in the cavern when the man who put Miss Hawthorne into the chest returns, and they see all the paraphernalia for the Black Mass still lying around. Miss Hawthorne notes that the gargoyle is gone.
The Master is no longer there, but the verger does come down into the cavern, and he and Benton get into a knock-down fight before the sergeant and Miss Hawthorne can flee.
Just as all three of them exit the church, there’s a minor earth tremor that’s felt all over Devil’s End, followed by a wave of heat that’s enough to warm the Doctor up and bring him back to consciousness.
Benton and Miss Hawthorne escape while all this is going on, but just as he gets out the church door, the verger is zapped and disintegrated by the unseen creature.
Now that the Doctor is up and feeling fully thawed, he says that the burst of heat was “the final confirmation of my theory.” He’s about to go back out to the barrow site, when Miss Hawthorne brings the injured Benton in. Our heroes finally all meet up at the pub.
While the Doctor is still sympathetic to Miss Hawthorne’s warnings and tells her “It’s a great pity they didn’t listen to you in the first place,” he dismisses her claim that she saw the Devil this morning as “nonsense”. 
Her description of a 20-to-30 feet tall horned creature strolling around should mean something to Mike and Benton, however.
And it’s from Miss Hawthorne that the Doctor hears the name of the new vicar who’s conducting other kinds of masses in the cavern.
Fortunately, the Doctor knows his Latin and makes the Magister = Master identification clear to Jo and anyone else who doesn’t.
Meanwhile, Brigadier Lethbridge-Stewart has phoned HQ to learn that all his team has gone galivanting off to Wiltshire after devils, and they’ve taken “MY helicopter!” He heads off after them and eventually runs into the other effect of this morning’s daemonic awakening: There is now a barrier that encircles the village a mile out from its center at the church. This barrier looks like a burnt circle of ash about three feet wide on the ground, but anything that attempts to cross it bursts into flames.
After he’s tried a few different roads into Devil’s End, with the same result, the Brigadier summons more UNIT specialists to figure out how to break through and contacts Mike Yates on walkie-talkie (a precursor to the mobile phone).
Once Mike brings him up to date on the situation in the village, the Brigadier sums things up:
“I see… The Doctor was frozen stiff as a board and then revived by a freak heat wave. Benton was beaten up by invisible forces, and the local white witch claims to have seen the Devil.”
He also learns that the Master is at the bottom of all this.
The Doctor and Jo have driven back out to the barrow, where they find the dead constable. They don’t notice the little gargoyle from the cavern cavorting up on top of the mound as they go inside.
They venture inside the tomb at the heart of the barrow, the sealed place that the doomed Professor opened at midnight to release a blast of frozen wind. There is no snow now, but there’s nothing inside the circular, stone-paneled room that would make it a tomb either–no grave, no grave-goods. Just a miniature model of a classic “flying saucer” spaceship sitting right at the center that Jo thinks must be stuck to the dirt-covered floor since she can’t pick it up.
No, it’s not a model, the Doctor informs her. It’s a real spaceship, shrunk down in size but retaining its normal weight of several hundred tons. It belongs to the “devils” or Daemons who have featured so much in the local legends. 
Because they are now active again, everyone is in great danger. Not just here at Devil’s End. The whole world.
While the Doctor is telling Jo about the Daemons, who came to Earth thousands of years ago, the little gargoyle has come leaping down from the top of the mound and entered it. He now stands behind the Doctor and Jo, blocking the way out.
