An Undisclosed Tomb

A tomb old enough that Harley Warren believed a book he carried could open something beneath it worth the risk of two men's sanity. Only one of them came back up, and he has spent every retelling since leaving out exactly where the hole in the ground was.

Whereabouts: Location withheld by the sole surviving witness, who states only that it lies in ‘a very ancient cemetery’ whose whereabouts he refuses to specify, for reasons he considers self-evident.

Access: On foot, at night, with lanterns and a portable telephone line run down into the vault — Warren's own chosen method of staying in contact with Carter, who waited above and never went down.