Blue Lights returns for its fourth season on BBC One

The Belfast-set police drama Blue Lights returns to BBC One tonight at 9pm with its fourth series. Within the first half hour, viewers are given an intense sequence touching on several topical issues — cuts to policing budgets, the migration crisis, livestreaming culture and the shifting meaning of nationalism. Despite covering so much ground, the show keeps its sharp thriller pacing, while its personal storylines add emotional depth.

Elsewhere on the schedule, Channel 4 airs a new episode of The Great British Bake Off at 8pm, focused on biscuit week. Contestants face three challenges: American-style cookies, a nostalgia-themed technical test, and a mosaic-patterned showstopper. Chef Nigella Lawson has joined the judging panel this season.

At 9pm on BBC Three, Stacey Dooley Sleeps Over USA follows journalist Stacey Dooley to Oklahoma, where she meets nine-year-old "guntuber" Autumn, who has been filming videos on the subject since she was two years old.

On U&W, the documentary series Paul C Brunson: Red Flag reaches its concluding episodes, with relationship expert Paul C Brunson meeting Hannah, who experienced escalating abuse from a former partner, and Melanie, who was targeted by a romance scammer.

Channel 4's Tempting Fortune continues at 9.30pm, following contestants trekking across Malaysia in intense heat and humidity while trying to resist temptations — such as frozen treats, cold drinks and spa visits — that would reduce their prize money.

Finally, BBC Four's documentary The Three Kings, airing at 10pm, explores the careers of football managers Matt Busby, Bill Shankly and Jock Stein, all born within 30 miles of each other on Glasgow's south side, examining how their shared upbringing shaped their success.