It begins. The famous heart specialist is driving his BMW home from a hard day at the cutting edge, when a blonde American beauty pops up on the back seat and begins to undress. Here at last is a chest best left unopened! This is nice for him - but doubly nice for us, for we happy viewers now know that we are in the wonderful land of sex and surgery. We can look forward to lubricious interludes involving boobs and buttocks, and a denouement drenched in blood and tears. Nothing could be more satisfying than this.

And The Heart Surgeon (BBC1, Sunday & Monday) did not go on to disappoint. Nigel Havers, (whose skinny wistfulness is apparently immensely attractive to those immature women unaware of the pleasures to be had with larger, louder men) played the sexy doc with that semi-detached Englishness that is his trademark - and which appears like under-acting until you consider that many Englishmen are exactly like this. Like Havers, their idea of a change of clothing is to swap an oatmeal arran sweater for a light blue arran sweater. He hardly blinked when his contemplation of the emerging breasts was interrupted by a call concerning an "RTA with a transected aorta".

So it's swiftly into hospital, where the link between the real, fleshy organ of life and the metaphorical source of emotional life is enhanced by the presence in our hero's theatre of a woman psychologist doing an MD "in the emotional effects of heart surgery". Though upon whom - the doctors or the patients - is left open. Or rather, since patients rarely show much emotion during open-heart surgery (beyond continuing to live, or inconveniently dying) we must assume that she is studying the doctors.

Enter the complication: an old friend with a dicky heart and his beautiful wife. She - naturally - is Irish. Since the rise to stardom of Dervla Kirwan, Irishwomen have become very popular; they are passionate, earthy and ethical. This one leaves the farm, the hay and the manure - and comes to town in an Agnes B top and slinky black stockings. She is clearly up for it.

They ponder an affair. She is in the bath distractedly soaping her breasts, he is in the kitchen distractedly chopping his peppers. Her breasts are pert, his chopper is shiny. We are in for a heart operation of another kind.

What kind is never in any doubt. Next morning we discover them asleep. We know that it has been a night of rare passion because he is lying naked on the bed and she is lying naked on the floor. How did this happen? Did she fall off the bed during the night? Or is there a position that only doctors, farmers or the makers of prostheses know about? Whatever.

Now sex gave way to the surgery, as Havers was forced to operate on the husband. This incredibly detailed procedure was absorbing, well-acted, and terrifying. It surely must have raised the blood pressure of those expecting heart surgery to dangerous levels. I mean, what happens if you're lying there on the table, your body opened from neck to navel, stuffed full of plastic tubes and linked to a dozen bits of bleeping electronic gizmos, and the surgeons attending to you begin to say things like: "So what's it like being Superman?" and "I don't know. What's it like being an arsehole?" One has your quivering ventricle in his hand, and the other holds the pulsing bloodline. Brilliant.

On Channel 3 they introduce the "ITV drama premiere" with a friendly voice, speaking over a long tracking shot of a well-heeled suburban street in mid-evening. This now tells you that you just have time to put out the cat, make a cup of tea, unpack the car and nip down the polling station and vote the Tories out. Then the camera pans and we discover that the voice belongs to Pete Postlethwaite, wearing angel's wings. Not really.

We could do with Pete returning to help out in the continuing Napoleonic saga Sharpe (ITV, Wednesday). Sean Bean, beefcake for those un-Havering ladies who prefer rough to smooth, is in need of assistance, for the drama is not working.

One, it's formulaic. Sharpe storms hills, fights duels with cowardly, sneering aristos, is framed for a crime he hasn't committed, and then proves his innocence. Yawn.

Two, its characterisation is lazy and incredible. Sean has a wife, Mrs Sharpe, a cipher with two creamy blancmanges for bosoms, and one more for a brain. How someone so utterly moronic is supposed to have stolen the heart of the rugged individualist is beyond me. But since she (like virtually all the characters, save one) only exists to prod the silly plotline along, it seems not to matter.

Three, the location is strangely inconsequential. Most of the time we simply do not know where we are; the geography and distance are bizarre. Various factions occupy nondescript and scrubby bits of what the credits reveal to be the Anatolian plateau, from which they ride out randomly to assault each other. No wideshots establish where anything is in relation to anything else.

At one point Sharpe must get from Toulouse to Normandy. This is 1814, so it takes several days. Passing through a wood, he suddenly looks up from a cabbage cart and says to his sidekick, "Normandy! We're nearly there!" How did he know? Could he smell Calvados? And, a minute of two later, "a Naples!" is the cry, and they are in Naples (an epic journey in those days).

Four, the battle scenes are disappointing, employing a static camera to capture various conscript privates in the Turkish army running at the enemy, shouting "Graaargh" and falling over. Again there is no sense of being there. This is what happens when you film an epic to a sitcom budget.

Many programmes get round this problem through the use of dramatic reconstruction to tell extraordinary true stories. I personally cannot wait till next week's 999, which - according to the trails - will offer us the story of a camper: "He's on fire, he needs help, but he is alone and on an island." The answer must be smoke signals.

But this week there was a special edition: Missing in Action (BBC1, Tuesday) - the tale of the American fighter pilot shot down over Bosnia. I rather liked this being a 999 Special, as though pilot Scott O'Grady's options included calling out the Hampshire plod or the Essex fire brigade.

The trouble with reconstructions, however, is that they are often ludicrous. Storms must be re-enacted on calm ponds, lest the actors be placed in any danger; men roll gently down soft slopes rather than fall off cliffs. And sometimes - as here - nothing much happens to reconstruct.

Scott himself parachuted from a burning plane and hid in a Bosnian wood for a week. Then he was rescued. The wood, as depicted here, possessed all the savage natural majesty of Richmond Park in late spring (though with less dangerous wildlife). Every now and again an armed Serb - looking about as threatening as a park-keeper with a pointy litter-stick - meandered past, scowling in a Mediterranean way. Scott himself passed the time by putting his beret on (albeit very carefully), drinking some rainwater and eating a few ants. He was on his fifth when they picked him up.

This being a tale that the miltary wanted told, the list of co-operators in the credits had a martial flavour. But on the same night at the same time a true drama began with a different message. "This film was made without the co-operation of the Ministry of Defence," it said.

The story told in The Investigator (Channel 4, Tuesday) was that of a woman member of the military police, Caroline Meagher, who spent several years weeding lesbians out of the armed forces, before discovering that she was gay herself. The investigator was investigated and she was hounded out.

This excellent film offered us two lessons, one witting and the other - I believe - unwitting. The first was about hypocrisy and intolerance. As one lesbian says, "We make the best soldiers. They couldn't manage without us", yet they are hounded and persecuted. Most chilling was the perverted logic that demands the extraction of salacious details from confused young women, because the army has to separate the real lesbians from those who may simply be looking for an easy way out.

The second was less obvious and remained unexplored. A section of the film depicted a base in which favours seemed to be being handed out to lovers of the gay officer in charge. This suggested that there are genuine dangers (equally true for straights as for gays) when sex is permitted to rule. True in drama, true in life: sex makes monkeys of us all - from those whose job it is to kill, to those whose job it is to save.