Unforgotten on Masterpiece

Sunday, Aug. 1, at 8 p.m.

Sanjeev Bhaskar explains the social media hype about Sunny’s iconic backpack, and how it has evolved over the years.

Stars Nicola Walker and Sanjeev Bhaskar are back as the crime solving duo DCI Cassie Stuart and DI Sunny Khan, with writer/executive producer Chris Lang and director Andy Wilson back at the helm in this fourth season.

In the series’ most dramatic season, Cassie and Sunny investigate a cold case with alarming links to the police force. Can the force ever really be trusted, and will Cassie and Sunny find themselves on the wrong side of the law? See the preview for this week’s episode.

WATCH NOW: Catch up on Seasons 1 – 3 with access to PBS Passport.