Jeb and Blake go in search of John the Baptist's resting place.
Content Warning: Human remains on screen. Discussion of murder.
Beheading John the Baptist (wiki)
In 2018 the murder of Bishop Epiphanius took place and rocked the religious community -- not important for this episode but it popped up a lot in my searching.
San Silvestro "head" shown in intro
Nimoy Fashion Alert
(NFA Wardrobe consulting by The Hogtown Rake, Pedro Mendes)
The "head" of John the Baptist at San Silvestro:
Art historian Michael Patroconni (Petroccione?)
I think Jeb and I found this to be the most fun part of the episode: