Northern Irish police drama Blue Lights returns for season three. Plus, Prof Jim Al-Khalili gets inside our heads in a Horizon two-parter on the human brain. Here’s what to watch this evening Northern Irish police drama Blue Lights returns for season three. Plus, Prof Jim Al-Khalili gets inside our heads in a Horizon two-parter on the human brain. Here’s what to watch this evening 9pm, BBC One Love is in the air as we rejoin Belfast’s peelers for a third season of the award-winning cop drama.