“World Killer” is episode five of season four of Sliders.
The Sliders are leaving a cinema – Maggie doesn’t see how any world could make Bogart a star – and slide out in an alley. They slide back in in the same alley, despite the 400-mile radius, to a world generally identical. Except the streets are littered with abandoned vehicles and there are no people. Or bodies. Quinn thinks whatever happened did so a couple of years ago. Rembrandt suggests Kromaggs but Quinn says there are no blast marks or rubble. Maggie suggests biowarfare as she opens a police car. Rembrandt says everything is dead. As two dogs attack Quinn. Maggie scares them off with the shotgun she found.
They arrive at Quinn’s house on this world. He knocks; Maggie just opens the door and calls out for any Mallorys. There are some trophies that Quinn recognises. Science prizes he tried for but didn’t get. This world’s Quinn did. And on this world his mother died when he was young; he was raised by his father. Quinn thinks this Quinn is better than him. Maggie reassures him he’s no slouch but Quinn says he can’t reprogram the timer with the coordinates of his brother’s world. On each world he hopes for a physicist to help.
They decide to check the basement, which has been trashed. Quinn wants to have another look around whilst the other two head outside. Maggie says Quinn is hurting and she knows how he feels. Rembrandt says with Quinn being from another world, Maggie’s world blown up and his overrun by Kromaggs, they are all shipwrecked one way or another. But floating on the same piece of driftwood. Rembrandt wonders what’s taking Quinn so long and heads to call for him. As someone is creeping up behind Maggie. It’s another Quinn and he hugs her. She’s real. Yes, but not from here. Rembrandt asks where everyone is. Quinn Two built what he thought was an antigravity machine and it wiped every human being from the face of the earth.
Inside, Quinn Two says this happened three years ago. Everyone vanished. Quinn says Quinn Two’s device must have been more powerful. Quinn Two said a wave of light spread out. A sliding wave. Quinn Two says he did everything right. Except test the device, according to Quinn. That was the test. Quinn Two realised that they might have been sent somewhere, but he couldn’t get them back. He tried to replicate the experiment, but couldn’t and smashed everything up. Quinn asks about notes and diagrams so they can rebuild the equipment and find out where everyone went. Quinn Two thinks that’s impossible; Quinn tells him they’ve learned a trick or two. The notes are ion the storeroom. When Quinn Two has gone, Rembrandt says he seems col-hearted. Quinn defends Quinn Two, but Rembrandt thinks they might be cut from a different cloth.
With the notes found – and it seems Quinn Two has felt overshadowed by his father; Maggie gets that – they head to an electronics place. Quinn Two still doesn’t think this will work. Quinn picks up a biomed scanner; if there are other humans on the other world, it could tell the difference between them.
The new machine is built; it’s small and Maggie asks if it was powerful enough to slide a whole planet. It seems the original was smaller but Quinn Two crashed the entire West Coast power grid in a test. Rembrandt joins them. He’s picked up some money and a mint Superman 1. The machine is activated and Quinn picks up the machine to slide with them. They slide out into the same basement. A kid comes downstairs, then runs back up. They follow. There are many people upstairs. Including a nun with a gun. She tells Maggie to drop hers and another nun – the first one’s twin – advises her to do so.
The nun, Sister Celine, with the gun how they go through the tripwires, razorblades and dogs. She’s told they didn’t get through them, but the sister doesn’t believe them. She also doesn’t believe they don’t know what happened three years ago. The other Celine starts by talking about the Great Flood, but the world became as it had been. This time God brought a terrible judgement. Five billion people became ten overnight. Hell was made manifest. Quinn two says he did it. He wants to activate the machine to demonstrate, and does over Quinn’s objections. It catches fire after creating a wormhole. Sister Celine still isn’t impressed. Rembrandt has another demonstration. They have money.
Sister Celine ends up being convinced. But now they need to rebuild the machine again. And this world is ruled by warlords. Quinn is finding his alternate to be a bit of an uncaring jerk.