Obsession

A few months after the fire that injured Leslie Shay and Peter Mills, Severide, Casey, and Dawson discover the first clues that it might have been arson. With everyone still struggling to recover from the trauma of the call, digging into what happened puts their fragile healing at risk. Despite this, none of them can let it go. AU of Chicago Fire S3E11-13 & Chicago PD S2E13.