Death In Paradise (BBC1, 9pm)

BRIGHTENING up the winter months with comedy crime, BBC1 returns to the Caribbean shores of Saint Marie for the sixth series of viewers’ favourite, Death In Paradise.

In the first of this eight-part series, DI Humphrey Goodman and the team are left stumped when volcanologist Stephen Langham is found dead halfway up a live volcano, after failing to return from a night shift.

With all evidence and the pathologist report pointing towards a heart attack, death by natural causes is suspected by all. Humphrey, however, is convinced that one of the observatory team had a part to play in Langham's untimely demise. With the security swipe-card system providing each of the three other scientists with an alibi for the time of the murder, how could any of them have committed the crime?

Unable to find any physical evidence of murder, the team have a tough task ahead of them. Puzzled by some seemingly missing equipment at the scene of the crime and the timely presence of Saint Marie’s mayor, Humphrey soon discovers that Stephen and his colleagues, including his brother, didn’t always see eye to eye. With everyone hiding secrets, will the team be able to find out who killed Stephen and why?

Meanwhile Humphrey is excited by Martha’s return to the island for a summer holiday. Is romance finally blooming for Humphrey? Elsewhere, JP is settling into married life while Dwayne risks angering the Commissioner when he lets his guard down with a local journalist.

The Money Saving Diet Show (ITV, 8pm)

A new year has begun, a time for taking stock and working out what we want from life – and, of course, for getting rid of those extra pounds we put on during the festive season. If you're looking to improve your health but are struggling to find the best way to do so, then this programme may help. Presented by Sian Williams and Ranj Singh, it charts the progress of six overweight Britons as they attempt to stick to six popular diet regimes for four whole weeks, including Lean in 15, Paleo diet, 5:2 and Lighter Life to Juicing. Along the way the hosts also reveal how eating healthy food can also cut your shopping bills. It sounds line a win-win situation, but how easy is it to stick to? We're about to find out.

The Restoration Man (C4, 8pm)

NEW series. Wearside-born George Clarke returns to witness more neglected architectural treasures rescued across Britain. Young couple Steven Crame and Marina Bacchelli were looking for their first home together in Berkshire when they found a disused water pumping station in its own ancient woodland – ideal to convert into a four-bedroom family home. The couple throw themselves into the task of transforming the huge brick shed their new house, while preserving a 15-ton crane as a central feature of the lounge. It's a tough project – and spiralling costs, flooding and a newborn baby only add to the pressure.

Unforgotten (ITV, 9pm)

IT'S been a long time coming, but at last, the second series of this acclaimed crime drama is about to begin. Nicola Walker and Sanjeev Bhaskar return as DCI Cassie Stuart and DS Sunny Khan, who have another intriguing case to solve. This time it involves the discovery of a body found in a sealed suitcase in the silt of the River Lea. The corpse is well preserved, and turns out to be that of David Walker, a middle-aged man who disappeared in 1990, leaving behind a wife and young son, who is now in his early thirties. But who wanted him dead and why? That's what Cassie and Sunny have to find out, and their investigation leads them to four seemingly unconnected suspects, including a fellow member of the police force.

"The gap between series means it's not as easy as you might think to walk straight back in just because you're wearing the correct costume," says Walker. "You hope we can serve it as well second time round. But actually three or four days in it felt really good to be back playing her."

Viv Hardwick