Back to Sid's filmography: This is a re-scripted version of the second in a four part series on the history of cave diving, which was based on Martyn Farr's book The Darkness Beckons. The film starts with a reconstruction of Bob Davis and Don Coase linking the Peak Cavern resurgence pool with Swine Hole in the cave. This is followed by a reconstruction of Bob Davies's near miss when he was diving in Wookey Hole, supported by John Buxton and Oliver Wells. He lost the line, and and found himself in the previously unknown Chamber 15. He managed to retreat back to base with minimal air and no line. The film then describes Mike Boon's move to small air bottles and fins, and reconstructs his dives in Hardrawkin Pot and the passing of Sump 7 in Swildon's Hole, before finishing with a reconstruction of Ken Pearce's world record breaking dive in the Gouffre Berger. The film features interviews with Mike Boon and Ken Pearce. The divers involved in the film include Rupert Skorupka, Geoff Crossley, Ken Pearce, Peter Eckford, Bob Cork, Dany Bradshaw, Mark Robson, Dave Turner, and Ian Watson. It was originally shown on BBC One on September 26 1989.