Agatha Christie’s Poirot: The Labours of Hercules (8pm, ITV)

Writing this episode must have been a Herculean labour for Guy Andrew. Heroically, he’s managed to cobble together some unrelated ingredients from a book of short stories by Agatha Christie and stitch them all together, reasonably neatly, into one big, fat mystery.

Joining David Suchet for  this penultimate story are Simon Callow, Orla Brady and Fiona O’Shaughnessy in a very different guise to the assassin she played in Utopia.

Poirot is on the trail of a missing lady’s maid when he checks into the opulent Hotel Olympus in the Swiss Alps.

 He discovers that one of the guests, or maybe even one of the staff, is an infamous jewel thief and murderer who has eluded him before. And when an avalanche cuts off the hotel, they’re all trapped until the killer can be unmasked.  But with the stunning backdrop of the mountains behind them, there are worse places to be marooned.

The guests all come with heaps of baggage – there’s a fragile ballet dancer, her Austrian doctor, a hatchet-faced mother and daughter, and the kleptomaniac Countess Rossakoff who is an old friend of Poirot’s.

There’s also a small dog who threatens to upstage the lot of them.  With so many inter- connected mysteries to solve, Poirot’s summing up is especially epic.

Ambassadors (9pm, BBC2)

A rebel uprising rocks the British embassy in Tazbekistan tonight as this very short series comes juddering to an end.  But British ambassador Keith Davis (David Mitchell) and his unflappable deputy Neil Tilly (Robert Webb) are also put on the spot by the arrival of a government vetting officer (Michael Smiley) whose razor-sharp interrogation techniques makes him a big hit in some quarters.  And the ambassador’s wife goes shopping with the President’s pop-star daughter.

With deadly serious bits and mildly funny bits, Ambassadors has never really gelled into a shape you could totally relax into. While Matthew Macfadyen is excellent as the bombastic Pod,  and Susan Lynch can turn her hand to anything, Keeley Hawes and the rest of the supporting cast somehow suck all the atmosphere out of their scenes.

Misfits (10pm, E4)

In its final series Misfits is still able to surprise us and it does so again tonight when amnesiac Abbey discovers the reason why she’s been strangely drawn to the heavenly-smelling Laura.  “I thought I was a lesbian with acute memory loss,” she tells her friends before completing that sentence in a way no other series could get away with.

The ending to this particular storyline is a bit of a let down though and it’ll be interesting to see whether Misfits intends to do anything we haven’t already seen before with Sam, the lad who can fly – exactly as prophesied by the woman who can knit the future.

Elsewhere, Greg (Shaun Dooley), has been enjoying an unusually long innings for a Misfits Probation Officer, but that could all be about to change tonight as he experiences The Power Of Love in some hilariously awful scenes that are as far removed from John Lewis’ snowman as it’s possible to get.   You have to give Dooley points just for keeping a straight face.

SOAP ROUND-UP

Emmerdale (7pm, ITV)

Now that Sam knows Jai is Archie’s real father, he’s finding it hard to forgive Rachel for lying to him. Telling lies just isn’t in Sam’s nature, so how long will it be before he blurts out the truth to Charity? For the time being, he’s just content to confront Jai with the fact that he knows his secret.  Elsewhere, Bernice and Jimmy are getting on famously – but keep your eye on Gabby who’s about to play a sneaky trick on the pair of them.

Coronation Street (7:30pm ITV)

You’d have been gutted to have Roy Cropper as your neighbour in an episode of Changing Rooms.  He’s a lovely man, but he’s got no business messing about with interior décor. Despite this he’s trying to spruce up their bedroom as a surprise for Hayley.  And surprise her he does. If  she weren’t already planning on ending her own life, I reckon that wallpaper would be enough to tip her right over the edge.