Voices of the Valleys

8pm, Sky Arts
Gwlad! Gwlaaad! A gorgeous three-part documentary following male voice choirs performing “a sound that can put shivers down your spine” at competitions across Wales, and getting to know why they’re such an important part of their communities. It starts with the Beaufort Male Choir – whose tenor and soloist Callum Rees will melt hearts as he puts his busking earnings towards the choir. Hollie Richardson

Casualty 24/7: Every Second Counts

8pm, Channel 5
The big red phone never stops ringing at Barnsley A&E, as cameras follow ward sister Jo. It’s an episode defined by the old and the very young: while elderly patients are fainting, collapsing with suspected strokes or struggling with weak hearts, a three-year-old’s cut lip might be severe enough to see him relocated to Sheffield. Jack Seale

The Undeclared War

9pm, Channel 4
Despite the best intentions of everyone involved, Peter Kosminsky’s cyber thriller refuses to catch fire. However, it has at least managed a decent smoulder by the end of this penultimate episode, in which Danny, Saara and Roz join forces to help Vadim escape. Then Danny makes a discovery that changes everything. Phil Harrison

999: Critical Condition

9pm, Channel 5
To Queen Elizabeth hospital in Birmingham, where care teams calmly tackle potentially life-changing injuries. Among the patients benefiting is pensioner Graham, who needs a multipart surgical operation to remove a sinister inner ear tumour before it puts him in a coma. Graeme Virtue

Guy Montgomery’s Guy Mont-Spelling Bee

10pm, BBC Three

Self-effacing speller Tom Walker is back to defend his title in the second series of Montgomery’s charmingly 70s-esque gameshow. But he didn’t bargain on Hannah Gadsby’s hidden talents or Lloyd Langford’s Welsh advantage. Come for the ridiculous job title guessing game, stay for the struggle to spell the audience’s names. Hannah Verdier

The Big Cases: The Funeral Home Horror

10pm, BBC Two
A look at the upsetting case of undertaker Robert Bush, who last week was in court for offences including selling fake funeral plans, giving the ashes of strangers to grieving families and preventing decent burials. The people betrayed have since been fighting for laws to make sure this never happens again. HR

Live sport

The Hundred Cricket: Trent Rockets Women v Birmingham Phoenix Women 2.45pm, BBC Two. Followed by Trent Rockets Men v Birmingham Phoenix Men at 6pm.