"Every decade, an Authority representative visits. We reject his offer for help-now we plead for aid. Brother Niccoli is murdered. Brother Andrew is missing, None of us dare enter the Crypt. We pray God protect those that will..."

Hellbound recounts the events leading up to the RPC Authority Vesuvian monastery containment operation (codenamed "Operation Sub-Vesuvia"). The monastery in question was home to The Order of Saint John monks, located at the foot of Mount Vesuvius.

The Order's monks swore an oath of silence and seclusion in order to protect the many technological wonders from the great mind of Leonardo Da Vinci as well as grotesque hell spawns contained in their Crypt.

Just recently, The Order of Saint John undone the veil of silence and reached out for aid from the RPC Authority. After the initial contact, it was discovered that the security of the Crypt was compromised and that one of the monks had been murdered, while another one went missing. With the Monastery's secrets at stake, the Authority sent two of its most distinguished investigators from the MST Sierra-8 "Sundowners".

Will they find whatever secrets the Crypt is hiding inside its belly? Or will the path they take lead to more ash and blood?