The Winchesters, especially Dean, aired his suspicion about the British Men of Letters. Mary teamed up with them in a previous episode, and it even caused a huge argument between her and Dean. But now, it seems that Mary is beginning to cast doubts on the organization's true agenda as well, and in the next episode of "Supernatural" Season 12, she is going to do her own investigation.

BMOL and their secret

We know that Mary and Arthur Ketch have a past. Mr. Ketch has a very tough personality, and as a matter of fact, he is a very ruthless killer. He sees killing as a job, and he even said that if he is not killing, it bothers him, along with the British Men of Letters' ability to give him targets.

However, during that time with Mary, we saw that he has a soft spot, too. Some fans even thought that they could have a future together, but the next "Supernatural" episode may kill that possibility.

For "Supernatural" Season 12, episode 20, Mary gets suspicious of the BMOL. The official synopsis released by The CW revealed that Mary thinks that the Brits are hiding something, and so she will take matters into her own hands and do some investigating. She listened to Mr. Ketch's phone conversations, which seemed to confirm her doubts. The worst is yet to come.

Mary versus Mr. Ketch

The promo for the upcoming "Supernatural" Season 12 episode shows Mary in an intense fight with Mr. Ketch. She is able to fight back at first, but eventually, we see Mr. Ketch preparing some tools that look like they are for torture.

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How could he do this when they have a past? Executive producer Andrew Dabb said that Mr. Ketch puts duty first before anything else. What happened between him and Mary will not stop him from carrying out orders.

If you are wondering where Sam and Dean are, they are out hunting. Episode 20, which is titled “Twigs & Twine & Tasha Banes,” will also show the Winchesters helping Alicia Banes (Kara Royster) call Mary (guest star Samantha Smith) because their mother has been missing since she went out hunting for a powerful witch. Hopefully Dean and Sam make it in time to save Mary, too.

Meanwhile, "Supernatural" Season 12, episode 20 will also show the Winchesters lead a battle, Dabb said. The EP teased that the BMOL will start to get rid of Dean and Sam, including their friends, and the brothers will take a "much stronger role in the wider hunter community" as they fight against the Brits. “Twigs & Twine & Tasha Banes” will air on May 4.