Dex goes undercover as a high school substitute teacher after an old classmate of hers enlists her help to find out who planted drugs on her daughter. Meanwhile, Dex and Liz's relationship gets too close for comfort.

With Sue Lynn's help, Dex works to find a fellow veteran's birth parents after he discovers that he's adopted. Meanwhile, Ansel creates a birthday bucket list for turning twenty-one and enlists Grey's help to complete each item. Elsewhere, Grey continues to work with Hoffman and goes undercover to infiltrate a car ring operation.