The Mark of Cain
Channel 4, 9pm

It's Not Easy Being Green
BBC2, 8.30pm

The Bulls*** detective
BBC3, 9pm

Just like Tony Marchant's most recent TV drama, Recovery, The Mark of Cain began with a caption reminding us that while it was based on extensive research, it should be considered a work of fiction.

Just like Recovery, Tony Marchant's latest creation was also a meticulously researched and affecting work of dramatic power and complexity.

In depicting the lethal nightmare currently enveloping the British Army in war-ravaged Iraq, Marchant chose to walk the painful path of subtlety, narrative complexity, thoughtfulness and attention to even-handed detail.

Marchant's perplexed working-class squaddies patrolled the streets of Basra equipped with little to protect them from harm, aside from their own fast-diminishing humanity. "I'm gonna get shot in the back," one acidly observed as he ventured down an ominous back street.

Asked why, he spat: "Because I'm wearing body armour on me front." Such bleak gallows humour swiftly gave way to a hellish mockery of justice - the type of military barbarism we've all seen in photos from Abu Ghraib prison.

In the wake of a savage ambush which claimed two of their comrades' lives, the British squaddies demonstrated the insidious means by which conflict brutalises everyone who takes part in it. In the name of revenge, manhood and group trust, suspect insurgents were beaten half to death.

Portraying good young Brits gone bad under inhuman martial stress, Gerard Kearns (Ian in Shameless) and Shaun Dooley (wasted in Mobile) were riveting, spell-binding, harrowing. Were you watching, Tony Blair?

Dick Strawbridge would make a good prime minister. Environmental guru Dick has a moustache so generous it could house any dormice or voles whose natural habitat might be threatened with extinction. Dick's mouth is almost invisible beneath his drooping fronds, but you can tell he's always smiling.

In It's Not Easy Being Green, Dick travels Britain dispensing hope and reassurance to all those attempting to reduce their carbon footprint by knitting themselves shoes out of kelp. Such decent, heartening Strawbridge-worthy folk are everywhere in INEBG.

Strawbridgers take the trouble to learn about 200-year-old techniques for painting their homes in eco-friendly, non-petro-chemical fashion (all you have to do is spend ages heating up linseed oil and blending it with organic colour pigments). They smile as they master the application of medieval lime plaster. They are sent into paroxsyms by the revitalisation of a set of ancient Bakelite door handles, or discovering an alternative use for a newspaper (folding it up into fire-lighters for wood-burning stoves).

I puzzled for ages over The Bulls*** Detective's title. Is it a fashion show for male cattle (The Bull's Hat Detective), or does it concern the crime-fighting exploits of a shamus called Bullshoe? If so, why the asterisks? Then I watched the thing and the penny dropped.

As its vulgar-yet-simultaneously-weak-kneed title would suggest, The Bulls*** Detective has Alasdair Jeffrey, an accountant, or lawyer, or some other form of balance-sheet warrior, enlightening us lesser mortals with his superstar businessman's nous.

Alasdair used to be an exec for a mobile phone company; now he wants to be Duncan Bannatyne. Who said ambition was dead?

Alasdair's TV USP is stalking about looking fierce and giving a new, must-have entrepreneurial twist to an old Glaswegian stereotype. Alasdair's a tough-talking, hard-hitting, no- nonsense, straight-shooting kinda boss.

Just what we needed. Aye, right.

Alasdair's task is to save us witless ninnies from squandering our dosh on modern consumerism's inessentials. Last night, he was saving us from crystal healing and bottled water.

I've a question for Alasdair myself: do you think we button up the back?

david.belcher@theherald.co.uk