Matt, I was thinking the same thing. I won't be surprised if Walker and Prentiss are drugged and Walker dies but Prentiss is just in bad shape.
If that's the case, maybe Walker gets a stronger dose? Maybe Walker has a bad reaction to it (like an allergic reaction)? I could see Scratch intentionally giving Walker a deadly dose to mess with Prentiss and the team. Scratch loves mind games, and he could try to put it in Emily's head that it's her fault Walker is dead since she's the one who brought him on the team. Scratch could decide to kill Walker since he's the newest member. His reasoning could be to make the team upset and make them feel responsible.
That sneak peek was intense. Angry Reid! I'm glad he's angry. They've been dealing with this jerk since Spring 2015. That's more than 2 years now. Yeah, he was in prison for a year of that time, but still. He first became a problem in 2015.
I love though in the sneak peek that it went from calm to BAM! OH CRAP! in 4 seconds! Garcia was calmly telling Simmons that Reid would figure it out then they both have a heart attack when Reid throws the book at the window
It's nice to see Reid upset and worried about Emily and the team, and it's nice to see Garcia worried about the team and Reid.