The Sword of San Galgano

Your colleague, a young archaeologist who was on the trail of the mythical sword of San Galgano (which some scholars directly relate to the Excalibur sword), has disappeared. The only clue to his whereabouts is in a video message that has reached you, in which he desperately asks for help. Dare you unravel the mysteries locked within a temple lost in history? Will you be able to venture into it and rescue your colleague? And more importantly, will you manage to get out before the monks guarding it return from their guard change and find you?