Selección Terror: Paso libre al infierno

This is issue #215 of "Selección Terror" (Terror Selection), a Spanish-language pulp series published by Editorial Bruguera in 1977. The featured novella, "Paso Libre al Infierno" (Free Passage to Hell) by Clark Carrados, concerns Professor Richard Bennett, a history scholar. Bennett's friend Henry Fuller accidentally opens a letter addressed to Bennett from Augusta von Kammel, inviting Bennett to Castle Roteberg to research Franz Peter, Baron Von Altwihr, "the Torturer." Fuller suffers a sudden, inexplicable collapse. A week later, Bennett discovers the letter reduced to black powder with unidentifiable chemical composition. Using hypnosis, psychiatrist Dr. Launsdorf forces Fuller to recite the letter's contents, triggering violent convulsions that kill him. Bennett copies the recovered text and travels to investigate, troubled that the letter was addressed to him specifically, suggesting deliberate danger.