After a young man is killed in an unexplored subterranean cavern and his girlfriend driven mad by something she saw there, a track found at the scene cannot be identified with any known animal and thus a scientific expedition is launched to find out just what it is that is living there.
Director:
Writer:
José Elías Moreno
Profesor Díaz
Carlos Cortés
Dr. Pena
Kitty de Hoyos
Hilda Ramírez
David Reynoso
Jaime Rocha
Columba Domínguez
Laura Ponce
Javier Solís
Dr. Manuel Ríos
Carmen Molina
Julia
Ramón Bugarini
Apolinar
Carlos Nieto
Novio de Julia
Marco Antonio Arzate
Armando Acosta
Gerente de gruta (uncredited)
Roberto Meyer
Padre de Julia (uncredited)
Inés Murillo
Turista (uncredited)
Miguel Suárez
Psiquiatra (uncredited)
