On Supernatural Season 13 Episode 15, Sam and Dean are on the hunt for blood from a holy man. Sam does a search on the internet, and is able to track down a woman named Margaret who's a dealer in holy relics. The guys go to meet her, and she provides them with a name of a man who may have information on where they'd be able to get holy blood. 

The guys go to meet him, but are quickly challenged to find a skull which was recently stolen from a church in Italy. He promises them the blood of a saint if they can come up with the skull. Sam and Dean try to find the skull, but it leads them to a mobster named Scarpetti who also deals with holy relics. He wants the skull for himself, and he hires the guys to track it down, but promises them a large sum of money so they can pay for the blood of a saint. 

They're able to track down the skull, but are soon joined by Father Camilleri who is looking for the skull because it belongs to his church. Sam and Dean agree to help him track it down. 

The guys are able to track it down to a warehouse where they find out Margaret is the one who had the skull, and she is ready to sell it to the highest bidder. Sam agrees to go in and bids on the skull, but a shootout takes place. The police arrive quickly, and the skull is returned to Father Camilleri. 

While talking with Father Camilleri the guys find out the Pope dubbed him the holiest man. They quickly realize they can use his blood to help with the spell. 

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