Túnel de los huesos.

Based on a real event, this is the spectacular escape of seven prisoners in 1991 from the Villa Devoto prison in Buenos Aires, Argentina. In the process of digging a tunnel to escape, they make a bizarre and frightening discovery just as they are about to break through to freedom. One escapee promises to report their findings when they are all free and once out, he pays his debt to "the tunnel of bones,"sharing their macabre story with a local journalist, and ultimately the world.