TV tonight: Viola Davis's legal eagle teases out the truth

How to Get Away with Murder 
10pm, Sky Witness

Shonda Rhimes’ legal drama comes to a close with its sixth and final season. The secrets that have been teased throughout the show’s flash-forwards begin to be revealed in a suitably melodramatic reckoning that leans heavily on Viola Davis’s emotional performance as legal professor Annalise. Tonight, Davis reckons with the disappearance of Laurel and Christopher, while Oliver, Frank and Bonnie each have their own theories on how they went missing. Ammar Kalia

Britain’s Best Parent? 
8pm, Channel 4

Anita Rani continues on her contentious quest to crown Britain’s best – or perhaps most smug – parents. We meet Hannah, who believes in a parent-centric approach with her 10-year-old, while Mia and Adam do the opposite, prioritising the needs of their son and daughter above all else. AK

Mysteries of the Mekong 
8pm, Sky Nature

This week we dive into the natural diversity of the southeast Asian country of Laos, just one of the territories the Mekong river snakes through. Replete with rugged highlands, expect a glimpse of endangered wild tigers, stump-tailed macaques and cheeky Indian mongooses. AK

Ambulance 
9pm, BBC One

TV’s best ever paramedics doc is back, focusing tonight on St Patrick’s Day celebrations in Liverpool. So there’s some drunken hilarity but much more on NHS staff repeatedly happening on deep wells of domestic heartbreak and isolation. Tonight, the call handlers hold lives in their hands. Jack Seale

Gangs of London 
9pm, Sky Atlantic

The weeks of build-up finally pay off as the truth about Finn’s murder is revealed in tonight’s episode of the brutally violent thriller. The revelation sends shockwaves between the Wallaces and the Domanis, while Luan has to reckon with the consequences of his actions, and Vicky makes her play. AK

The First Team 
9.30pm, BBC Two

How do professional footballers fill the time between training sessions? This episode of the new comedy from The Inbetweeners’ writers explores various options. Petey plays pranks, Jack meets up with a girl he met online and wide-eyed American Mattie befriends a star midfielder. Ellen E Jones

Film choice

Ride Lonesome (Budd Boetticher, 1959), 11am, Film4
Not that lonesome for Randolph Scott’s vengeful lawman, saddled with outlaw-sidekicks Pernell Roberts and James Coburn, pretty widow Karen Steele and giggling gunman James Best. He’s out to find his wife’s killer but vengeance is bitter in this typically lean and mean Boetticher-Scott collaboration. Paul Howlett