There's actually two séances at this year's Fringe. This one happens in a rigged-up shipping container outside Summerhall. We're shepherded in, put headphones on, boom, the lights go out and the table starts to move. It's a good between-shows scare. One minute you're having coffee in the courtyard; 20 minutes later you've been possessed by a spirit. Ain't it always the way.
It's pretty fun and there's some clever stuff with binaural sounds and rumbly sensations in the container. I'd go as far as to say it's scary, though the entrance and exit setup does nothing to create atmosphere or sustain an illusion. It's all a bit Alton Towers – but at the very least, the queues at Alton Towers use the opportunity to set the scene. The whispering-in-the-ear bit is very effective, though even over 20 minutes there's a sense that the narrative (inasmuch as there is one) starts to drag.
The darkness is complete, so wandering minds can't really wander far. It's an oppressive, immersive effect. Worth a fiver for a 20-minute 'ride'? I guess you'd pay that at the shows.