These two chilling episodes aired as the two-part season finale of season six and are arguably the tensest two episodes in Grey's Anatomy history. When the grieving widower of a former patient goes on a murderous rampage, seeking revenge on the group of doctors — Derek Shepherd, Lexie Grey, and Richard Webber — who made the decision to take his wife off of life support, it winds up being the recently transferred residents from Mercy West who pay the biggest price.
These episodes mark the end of the journey for Drs. Reed Adamson and Charles Percy, but although they're the only casualties, several other characters come out of the episode significantly worse for wear. Derek, Alex, and Owen all get shot, while the stress of the situation causes Meredith to lose the pregnancy she had been celebrating earlier in the episode. In addition to the physical scars the doctors carry following the shooting, they all come out of the terrifying experience showing symptoms of PTSD, which manifests in numerous and varied ways throughout the next season.