Television preview: RECOMMENDED VIEWING THIS WEEKEND

It's called casting against type, and it's as good a way as any of kicking lazy casting directors up the pants. Last week we had Birds of a Feather Pauline Quirke as a murderer serving life in the excellent The Sculptress. This week it's that nice Kevin Whately from Inspector Morse and Peak Practice, as a wife-beater. The occasion is Lucy Gannon's thoughtful shocker of a drama, Trip Trap (Sat BBC1), and coming to think of it, it was a Lucy Gannon drama, Tender Loving Care, that cast Dawn French as a nurse who was bumping off her patients. And, while we're still making connections, Gannon was also responsible for Whately's Peak Practice, not to mention Soldier, Soldier and Bramwell. Commissioning editors must camp out on her front lawn.

Whately is frighteningly believable as the harrassed primary school headteacher given to breaking his wife's ribs as she reads in bed. And Stella Gonet hands in a virtuoso performance as a woman trapped between self-loathing and a closed fist. It's the sort of drama that makes you wonder how many potentially abusive husbands-to-be are amongst the contestants on The Shane Richie Experience (Sat ITV). This, in case you missed the hoo-ha surrounding last year's pilot, is a game show for intending couples, the winning pair being married there and then on TV. Perhaps the idea could be extended to a game show for dissolving marrieds - with the winning partner getting a quickie divorce and custody of the kids. Cynical? I'm only looking at the role models for those whose marriages have been televised in the past: Anne and Mark, Charles and Diana...

Remember The Red Light Zone, Channel 4's late night attempt (let's be charitable) to broaden the discussion of matters sexual on our TV screens. Their follow-up is called The Blue Light Zone, a season of programmes about the police, as if the TV schedules didn't already resemble the car park at New Scotland Yard. Actually, the only non-repeat amongst the four opening films is rather good. Subway Cops and the Mole Kings (Sat C4) goes on the beat with the NYPD officers responsible for policing the 5,000 souls who have made their homes in Manhatten's sewers and subways.

Witness against Hitler (Sun BBC1), meanwhile, stars James Wilby in the story of German aristocrat James von Moltke's brave opposition to the Nazis. It's all very worthy, but I have to admit to switching to remote here. I still remember the same territory covered by Dennis Potter's more interesting Christabel, the drama that gave the world at large its first glimpse of one Elizabeth Hurley.

The Natural World (Sun BBC2) looks at the wildlife that hangs out at one drought-stricken South African water-hole. Not another dwindling water- hole film, I hear you groan. Stick with it, is all I can say. Apart from the fascinating Darwinian dynamics of the situation, there are moments of high anthropomorphic comedy. Witness the crocodiles biting their tongues rather than snack on the baby hippo who is joshing them around. Mama is watching, you see.

And still on the subject of carnivores and parasitism, Bookmark (Sat BBC2) has a satisfying film about the (usually strained) relationship between biographer and subject, which neatly leaves the last word to Oscar Wilde, quoted here. "Every great man has his disciples, and it's always Judas who writes the biography."