Over six million of us enjoy visiting theme parks every year. They promise a fun day out for all the family. With thrills and spills, you can make memories to last a lifetime. But sometimes for all the wrong reasons, as when the smiles turn to tears, it can be all downhill!In this programme, ‘Highlights' include the magical Disney parade which turned into a nightmare when the famous fire-breathing dragon became an inferno in front of shocked onlookers. A catapult ride fails to get off the ground. Just as two thrill-seekers, a cancer-survivor, and a teenager, are waiting in anticipation of the heart-stopping ride, the cord, which should have flung them into high the air, snaps spectacularly before their very eyes. And we hear of one man's close call on the day tragedy struck the Smiler Ride. Young radio presenter Danny Simm was next-in-line for world's first 14-loop roller coaster and couldn't believe his eyes when two carriages crashed, leaving some riders with life-changing injuries.Other incidents include out-of-control rides, some crazy foreign roller coasters where safety just doesn't seem to be a thing, and the theme park that looked more like a ghost town… as there were no visitors to be seen. Plus, it's sink or swim - or both – riding the rapids when some boats capsize. While flying through the air in a slingshot, a man loses a tooth.Contributors in this two-hour special, narrated by Dermot Murnaghan, include former theme park workers, the president of the Roller Coaster Club of Great Britain Andy Hine MBE and thrill engineer and TV presenter Professor Brendan Walker.