In 2005, Schmidt and Jenko are high school students, one an honor roll geek, the other a cool, athletic underachiever. By 2012, they are rookie cops, paired together, on bike patrol yearning to make arrests. After a screw up, they're sent undercover back to high school to find the source of a dangerous synthetic drug. They mix up their names, and Schmidt gets the no-brainer classes where he auditions for Peter Pan and falls in love with Wendy; Jenko gets AP classes where he falls in with high-achieving dweebs. This second chance at high school gives Schmidt delusions of grandeur, which threaten the operation. Can they sort out their relationship as they stumble onto the bad guys?
