The third series of the popular crime drama aired this summer

Crime drama series Unforgotten has been commissioned for a fourth series, ITV confirmed.

Nicola Walker and Sanjeev Bhaskar will return for six new episodes as London-based detectives DCI Cassie Stuart and DI Sunny Khan, who unravel historic cases of disappearance and murder.

Each series of the drama focuses on a different cold case, and also highlights the emotional impact the investigation has on those involved.

Creator and executive producer Chris Lang and director Andy Wilson will both return for the fourth series, after working on the first three together.

Unforgotten, which debuted in 2015, has previously won a TV Bafta for Tom Courtenay’s appearance in the first season.

It also won a Bafta Scotland prize the following year for Mark Bonnar in series two.

The third series aired in July and August, and its finale was watched by an average of 6.9 million consolidated viewers, ITV said.

Chris said: “I am so delighted to have been asked to make a fourth series of Unforgotten.

“The reaction to series three was better than I could ever have expected (with more people watching the last episode than any other in all three series) and I cannot wait to discover what lies ahead for Cassie and Sunny, and to create a whole new cast of characters for them to grapple with.”