Check out the scenario in "Touching the Void" by Joe Simpson. Joe's companion was forced to cut the rope they were abseiling on thus (he thought) condeming Joe to a huge fall into a crevasse high in the Andes. This is a true story and the escape that Joe pulls off with a massively broken leg is miraculous.
BTW its obvious that the (American) producers of a certain climbing film ripped this story off in the usual Hollywood "Take a good story and turn it into bo****ks mode."