It is hard to believe that just a year before Clint Eastwood created the definitive loose-cannon cop in the first Dirty Harry film, he was talking to the trees in the smash hit musical Paint Your Wagon. Made a worldwide star through the unexpected success of the spaghetti western A Fistful Of Dollars in 1964 and its sequels, the lean, laconic Eastwood wisely chose to vary his roles - though playing a singing prospector could have been pushing his luck. Yet, whether it was sporting a flat-brimmed sombrero and poncho or a Magnum 44, what Eastwood's characters have all been is undeniably 'cool'. Ironically, he only took the character of Harry Callahan, the role with which he will be forever identified, after Frank Sinatra dropped out. Sudden Impact (Pearl, 9.30pm), the fourth Callahan outing, sticks to the reliable formula of maverick cop ridding society of its scumbags. This time, he is on the trail of Sondra Locke (Eastwood's then lover and co-star in many films) who is out to kill the thugs who raped her and her sister many years earlier. Unfortunately, the pacing falters and the violence is gratuitous, but then this is Dirty Harry and we know what to expect. It is worth staying up for Eye Of The Needle (Pearl, 1.40am), an unexpectedly good but low-key adaptation of the Ken Follett best-seller with Donald Sutherland starring as Nazi spy Henry Faber - the Needle. Only he knows the preparation for an Allied invasion of France via the Pas de Calais is a hoax. But as Faber carries his deadly secret back to Hitler, he is discovered and chased from London to Norfolk, then to the Scottish Highlands, where he finally eludes his pursuer. There, stranded on an island off the coast, Faber meets his nemesis in the form of a lonely woman (Kate Nelligan). The script is convincing and the characters believable. The Taking Of Pelham One, Two, Three (World, 12.55am) is a riveting thriller with the evil Robert Shaw holding a subway train and its passengers hostage; the sharp script is peppered with cynical humour. Man's Heritage (Pearl, 8.30pm) journeys to the murky waters of the North Sea, which is generally considered cold and hostile, provide some of the richest marine environments in the world. The film explores the complex web of life in the waters, and centres around the life-giving silver shoals of tiny fish. Huge basking sharks emerge from the green gloom, their gaping mouths filtering gallons of water and the tiny fish through their gill slits; each summer millions of sand eels hatch to feed on them, grey seals chase them through dense kelp forests, minke whales herd the shoals into dense clumps before engulfing them and millions of seabirds hunt the silvery shoals beneath the waves. Hats off to ATV for screening the NBA Game Of The Week (World, 9.30pm); with Cable's domination of British Premier League soccer, there is precious little popular sport on terrestrial TV and the more, the better. That said, basketball may be fast and furious - plenty of action for a televised sport, one would think - but there are those who believe it is only the last five minutes of the match that are worth watching. The terrestrial channels have the chance to retrieve a little soccer credibility by screening the replay of the British League Cup final between Middlesbrough and Leicester City on April 16. Neither channel bothered with the first final for which they are entitled to bid; get the replay and you'll make many viewers happy.