On FBI, Isobel Castille suffered a brain bleed after a bomb explosion at the end of Season 7. In the Season 8 premiere, it is revealed that she undergoes a craniotomy (brain surgery) to address the injury. Despite fans' fears that she might have died, Isobel survives the blast and her collapse, but her condition is critical and the team faces many challenges as they deal with the fallout of her injuries.