Gritty drama Kiri explores what happens when a social worker makes a tragic error of judgment…

Kiri. Wednesdays, 9pm, Channel 4/HD (CH 104/141). Find it in Catch Up > Channels > All 4

Sarah Lancashire (Happy Valley) plays Miriam, a hard-working and excellent professional who allows a little black girl under her care to spend unsupervised time with her birth grandparents ahead of her adoption by a white family.

But hours after she drops Kiri off at the home of her grandad Tobi (Game Of Thrones’ Lucian Msamati), the little girl is found murdered in a wood.

The finger is pointed at Miriam by the police, the press and even her colleagues for allowing the visit to happen. Sounds gripping, right? And as if the very presence of Sarah Lancashire wasn’t already a mark of quality, this four-part drama is written by BAFTA-winner Jack Thorne (National Treasure).