George O'Malley's mother comes to Seattle Grace for help after another hospital botches her surgery; a medical miracle inspires the residents; Jackson's suspicions about Mark and Lexie interfere with work.
After Tori fills in for her sister in a big musical showcase, she's asked to enrol at an elite performing arts high school. But once there, she wonders if she'll ever fit in.
Severide comes across a boy in need of help while out on a jog. Boden and McLeod clash over the future of the firehouse. Mouch and Greg Sullivan debate on Otis' podcast.
The firehouse crew goes to the scene of a railroad accident; Boden must make a big decision about his future; Severide learns more about the woman he saw with his father; Shay and Dawson continue to butt heads.
The shooting of a child in their neighbourhood forces Cruz and his brother to think about the gang, Isabella gets Mills to dress up for a gala, Casey feels sad he will be seeing Dawson less, and Shay gets in deeper with Devon.