An old friend of Shaky's, Guy De Malfeasance has been trapped in the wall of Weirdsister for 500 years. He has been nurturing a hatred for Shaky who he feels betrayed him to his fate. He tries, with Hobbes help, to force a way through the gates of power to a world of Negative magic. Is Hobbes truly evil? Is this the end of Weirdsister and the world as we know it?
Hobbes tries to run away from the cloaked figure, but the figure introduces himself as The Whisperer. He promises Hobbes all that his heart desires, but first he has to draw on the magic from the eggs.
Tim and Azmat are still working on their magic disco mixer, when they hear noises that they think are from the mixer. They try to turn the machine off when Jenny Wendle turns up, but it is off. The noise starts again. Milly, Cas, Starfinder and Shaky are there as Ethel runs towards them and tells them about the figure. At Misery's, Elaine tells Ben about an emanation from the wall, and she realises that Ben knows what's going on.
In Hobbes' room, the figure finds his notebook. It is Guy's book – the Whisperer is Shaky's friend Guy! He isn't angry with Hobbes for stealing it; had Hobbes not done that, he would have been trapped in the walls of Weirdsister forever. He explains a negative world within the walls of Weirdsister called the Seared Whisper, and if they can open the gate to this world, the Gate of Power, they will be unstoppable. But first Guy wants more Sorcerer's Eggs. He places a spell on Hobbes to make him do what he wants.
Shaky realises that the Whisperer will need more eggs, and Starfinder goes to destroy the accumulator. Shaky and Milly realise that the Whisperer is none other than Guy. Dr Wendle, Tim and Azmat turn up, and Shaky, Cas and Milly go to Hobbes' room. At the accumulator, Hobbes is making more eggs. Starfinder turns up and manages to damage the machine, but battles with Hobbes, who traps him in a Sorcerer's Egg. Cas, Milly and Shaky walk in on Guy. He attacks Shaky, and the girls try to stop him, but by casting spells on him they are just feeding him power. Guy traps the Professor in the walls, and the girls escape.
Shaky's head appears in the walls, he can see everything from there, and tells them to leave the college. They use the emergency exit, a spell that takes them to an unknown location. In Misery's, Ben won't explain to his mum what's going on, but she knows it's to do with the college. Dr Wendle and the students appear in Misery's – the emergency exit leads there. Elaine is so shocked she nearly faints.
Milly has to explain to Cas about Shaky's age, and Ben has to explain to his mum that Milly is a witch. She thinks it's wonderful, but Ben tells her that they're all in danger. Dr Wendle explains to the students that the man comes from the Seared Whisper, and the reason that the post of Beetle was created was to guard against such things. She remembers the emergency call button in the office. They need someone to go back inside the college. As the Whisperer's power decreases, so will his hold over Hobbes. They need someone with a connection to him. Milly realises that it is she who has to go in and talk to Hobbes.
The Whisperer is growing weaker, and he needs more energy. Hobbes is trying to fix the accumulator, but it is too broken. Guy tells him that there is someone outside who wishes to speak to him, and he will let Hobbes go, but he warns Hobbes that if he betrays him, he will regret it. Hobbes goes to meet Milly outside. They talk about that first day at college when Milly helped him with the All-Seeing Eye. Hobbes tells her that the story he told her was true, about him having made one big mistake. Milly tells him that the Whisperer isn't getting any magic from the eggs; he's getting it all from Hobbes. He tries a spell on Milly, but it doesn't work. She has proved her point. Hobbes secretly gives Milly a piece of paper.
Back in Misery's Milly and Ben are arguing over Hobbes' plan. They will lift the Containment Spell, Hobbes will leave the main door open and someone will slip in to distract the Whisperer. Ethel offers to do this. Hobbes will let the others in through the Common Room window and they will rush to the Beetle's Office and press the emergency alarm to get the Beetle back. The piece of paper that Hobbes gave Milly is a note for Tim and Azmat, they read it to themselves, and Milly gives Ben a hug before going off to carry out their plan.
Ethel goes to distract the Whisperer, but he turns her into a frog. Meanwhile, Hobbes has let the others in. They find Ethel as a frog and pick her up. Jenny Wendle and Milly go up to the office and press the emergency call button while the others guard the door. Thunderblast and the Beetle appear, and explain about the Seared Whisper. The Beetle rushes up to her office, thinking that someone has opened the Gates of Power, and comes back down with a scroll. But suddenly the Whisperer turns up and freezes them all. The Beetle has found the scroll for him, and he tells Hobbes to imprison them in the lecture theatre. But the students are to be brought to him again at midnight for the opening of the Gate of Power.
Ben creeps up on Hobbes and demands to know where Milly is. Hobbes tells Ben that he will ruin everything if he doesn't let him get on with his plan. He shows Ben the All-Seeing Eye, the most powerful device in the college, and the only one that uses negative magic.
At midnight, all the students are gathered with the Whisperer. He turns Ethel back into a human, and tells them that he has released Starfinder from his egg. He looks up at the Gauge of Humility, where the Eye normally rests. Guy reads from the scroll, and a curtain seems to appear under the Gauge. A figure in a cloak who calls himself the Doorkeeper appears, and sets down a box on the floor. Tim and Azmat quickly read the note that they had, and turn on their remote-controlled magic disco mixer. While they distract the Whisperer, Hobbes utters a spell and the All-Seeing Eye flies out of the box, and into the Gauge. Suddenly Professor Shakeshaft appears and says another spell. The Eye turns red and the Whisperer is vanquished.
Ben high-fives Hobbes, and Milly gives Shaky a hug – they have saved the world, but Shaky warns them that they will need to be forever watchful.