A prologue, occurring in the early 19th Century, sets the stage by showing the origin of the EVIL' and the woods.
Six young boys, entering adolescence all, comrades in the Boy Scouts, love to play pranks, talk, hike and enjoy being alive. At a summer scout camp only two of the boys, Tommy and Johnny, earned enough Merit Badges to suit their Scoutmaster. In the final Scout Meeting of their lives, the Scoutmaster admonishes them to go out and practice hard so they can get more Merit Badges at an upcoming Scout Jamboree.
The boys, knowing their parents will not allow them to go out alone one more weekend, lie to them and allow Johnny and Tommy to lead them on their last campout, so they can learn enough to earn more Merit Badges when they return.
They take a wrong direction, but are oblivious until they enter some sinister and mysterious woods late on their second day. In the afternoon they come upon a very old house of Spanish design. They enter, explore the downstairs (the second floor unapproachable because of rotted wood on the staircase), then settle down to eat and tell stories, reminisce and generally goof off as they always have done.
The night descends with several mysterious and ominous portents, as had their previous night camping out in the open. After even the indefatigable Tommy becomes scared enough to ask Johnny to come with him, they take a final walk down a long hallway to see who, or what, continues to come down the stairs. Stairs they could not ascend because of rotted wood and banister.
The fright Johnny receives is different from the horrors and strange effects on each of the other boys, as they begin to find out only the next morning. To their horror, the bravest of them all, Tommy, has been frightened so deeply, his hair has turned white and he can only babble incoherently and must be carried by the boys in order to escape. In their haste to leave that awful house they only later discover that one of them has not come with them!
The return to civilization and their homecoming leaves them broken as a group, nevermore to be merely boys and Boy Scouts.
Johnny returns nine years later to try to get the remaining boys, each now nearing twenty years, together for one last night before Johnny serves overseas in the U.S. Army. They receive permission from Tommy's parents to come see him, with one strong requisite: they must not even broach the subject of The House.' The reunion is joyous but strained. At the end of the evening Johnny, because of his own fears, did not see who or what was coming down the stairs that fateful night, is unable to stop himself from trying to get Tommy to remember what he had seen and to tell all.
In the end, Tommy is catapulted back into horror. Johnny's friends are broken hearted and the secret remains in the mind of a young man who has retreated into unreachable portions of it.