The model represents a poor soul who was locked away in a dungeon and forgotten, long having since died and his body reverting to its skeletal form. The skeleton remains shackled to a stone wall, bit of torn clothing hanging from it. A few bones from another prisoner litter the floor, along with a snake and a couple of rats. A stone section of the wall is inscribed, THE FORGOTTEN PRISONER.
To boost sales, Aurora did a deal with Aurora Publishing; their Creepy magazine carried a tale in its August 1970 issue telling the story of how the Forgotten Prisoner met his fate. Despite this, the model wsn't entirely successful (perhaps owing to its gruesome subject matter).
This model returned to the 1/8 scale of the original Monster releases.
Note: This model exists in three versions: the original from 1967 in the vertical box, pieces molded in mustard-colored plastic; the re-release for the Glow Monsters (box shown at right) in dark gray; and the Frightening Lightning (glow pieces, vertical box) in lighty gray pieces.