Kelly goes to Guelph on her own in search of the chemist behind Purple Rain as Sam’s health issues have her trailing behind. When she does catch up, Sam finds Kelly trapped in an explosive situation.

After learning that the entire purple rain operation has been compromised, Sam and Kelly drown their frustrations in work, discovering the best way to solve the case is to go back to the beginning.

The OCE team works together to exonerate Naz and stop purple rain. Kelly and Nathan go undercover, Sam talks to an old friend, and Naz scrambles to remember a detail that can help arrest a killer. Series finale.