This week, Dexter returns to the idiot box for a farewell season (Fox Crime, Wednesday at 10.50pm) and the charming titular serial killer we hate to love is a happy bunny. Six months have passed since Deb, Dexter's brash, pencil-thin swear-box of a sister, chose to shoot dead her innocent boss rather than her psychotic brother; but while the death of Maria LaGuerta may have solved all of Dex's problems, things are not so rosy at camp Deb. The former lieutenant has quit the Miami police force. She's also running full steam ahead down a path to self-destruction and won't be knocking back beers with her mass-murdering mastermind of a bro any time soon.

Dexter, meanwhile, returns to a life of normality, and butchery, and the chase is on to catch the latest killer in town, "The Brain Surgeon". Assisting on the case is a new team member, neuropsychologist Evelyn Vogel (Charlotte Rampling) - but is she all that she seems? After seven seasons of glorious moral contortions and far-fetched storylines made remarkably believable by the wonderful Michael C. Hall in the lead role, I somehow doubt the writers will hold anything back for Dexter's swansong. Can they really let him get away with it all?

The Australia Network is not marketed very well, so you may be unaware the fourth series of much-loved romantic comedy drama Offspring is already well underway (the fourth episode shows on Tuesday, at 10pm). Set in Melbourne's vibrant Fitzroy, it follows the story of kooky obstetrician Nina Proudman and her fabulously messed-up family as they struggle to cope with the unpredictable chaos of modern life. Thirty-somethings Nina and her partner, Dr Patrick Reid, are on a mission to get their disordered lives under control before their baby is born. Thankfully, Nina's relationships with bold and brassy sister Billie and loveable free-spirited brother Jimmy are as engrossing as ever. At times comedic, at others heartbreaking, Offspring is a quirky roller-coaster ride of family ups and downs, and the comparisons that have been drawn with Ally McBeal and Grey's Anatomy certainly don't do it justice. The show is compellingly heartwarming, as it bounces playfully along, but - SPOILER ALERT - the series finale will take a much darker turn.

Filmed mainly in Canada's beautiful Nova Scotia, new mini-series Moby Dick (Fox Movies Premium, beginning tonight at 11.30pm) is a "reimagined" (according to the producers) version of Herman Melville's epic 1851 novel of the same name. Told through the eyes of shipmate Ishmael, it stars William Hurt as the peg-legged Captain Ahab, a man driven by vengeance in the hunt for the big white whale that ate his leg for lunch. Assisted by a ragged crew, notably first and second mates Starbuck (Ethan Hawke) and Stubb (the ever great Eddie Marsan), Ahab's mission passes from weeks to months as the hunt intensifies.

Moby-Dick is a complex novel that doesn't lend itself to shorter dramatisation and this version certainly takes liberties with the original; notably in the addition of a wife for Ahab (Gillian Anderson; The X-Files). This tale of adventure may not satisfy the purists with its contemporary dialogue but the action makes for a gripping nautical ride for the casual viewer.