It is located on a counter inside the Sunday Brothers' cabin.
Jesus Sunday: We were at our bunker when the Scorchbeasts attacked Harpers Ferry. It took them less than an hour to burn the place down. When the attack was over, I thought Brianna was dead and that JD would return to his old self. When he didn't, I became suspicious. Then Brianna shows up at our cabin with a small group of survivors and everything became clear. She had conned JD, played him this entire time, pretending to love him to give herself and her friends an invite to our bunker. Well, there was no way I was going to let that happen. I told her she could march right back to her cave and find her own place to survive. When JD tried to stop me, I had to knock him out. That's when Brianna's people pushed back, and I fired some shots into the air to scare them away. Now I have to deal with JD, and damn is he going to be pissed.