Lewis (ITV, 8pm)

THE sleuthing skills of millions of amateur detectives haven't been taxed too far in already working out that if Laurence Fox is quitting as Detective Inspector James Hathaway then North-East star Kevin Whately was certain to follow as the title role, after ten years playing the "perfect" partners in crime-solving.

Lewis, also starring Angela Griffin and Clare Holman, comes to a close tonight as the popular drama concludes the two-part film What Lies Tangled.

Written by Nick Hicks-Beach, we've already seen an idyllic Oxford summer’s day torn asunder by a gruesome parcel bomb. The victim is eminent mathematician Adam Capstone, a genius in the field of Knot Theory and notoriously known as a man of carnal appetites.

For Lewis this is not just any case. With his six-month trip to New Zealand with pathologist Laura Hobson (Holman) fast approaching, Lewis fears that if he doesn’t impress CS Moody (Steve Toussaint), he won't be rewarded with another contract on his return. With relations and motives as tangled as the knots David spent his life unravelling, Lewis is in a race against time not just to find a killer, but to save his career and his relationship too.

Whately starred with John Thaw in Inspector Morse and first appeared on screen as Robbie Lewis in 1987. In November 2000 John Thaw and Kevin made their farewell appearance in the 33rd Inspector Morse film, a dramatisation of Colin Dexter’s final novel, the Remorseful Day.

Lewis was commissioned in 2005, with Whately returning as Inspector Robbie Lewis on January 29, 2006. Set five years after the death of his long-term partner Morse, Lewis found himself teamed up much younger James Hathaway, and reporting to a new boss in the figure of Chief Supt Jean Innocent (Rebecca Front).

Tonight's conclusion will be the 33rd episode of Lewis, and Whately says: "I feel incredibly fortunate to have shared a decade of fantastic worldwide success with Laurence and with the most brilliant crew, cast and production team anyone could wish for, and all that time with the loyal support of so many fans and of our backers ITV and WGBH ?Boston. Thanks everybody. What a ride it has been.”

Fox says: "What an extraordinary ten years. I feel so lucky to have worked with absolutely the best crew in the business on Lewis. I will really miss hanging out with Kev for half the year. I am however fairly confident that he will not miss my flawless Geordie accent between takes. Thank you so much for watching and supporting us."

ITV’s Director of Drama Steve November says: "We owe Kevin a huge debt of gratitude and, of course, many thanks too to Laurence Fox who has been by Kevin's side for the past ten years. We respect their decision not to continue into a further series and wish them the very best for whatever comes next."

MasterChef: The Professionals (BBC2, 8pm)

SIX aspiring chefs compete in the cookery contest, beginning with a test of their basic skills. The first contestants must make the French dessert, a Floating Island, while the remaining three have to cook a blue steak with a green peppercorn sauce in 15 minutes. Finally, the six chefs cook their own signature dish for judges Monica Galetti, Gregg Wallace and Marcus Wareing. It is their last chance to show off their culinary talent before three of them are sent home, and three become quarter finalists.

Imagine (BBC1, Regions Vary)

OPENING in 2012 at the National Theatre, the stage production of Mark Haddon's best-selling book The Curious Incident of the Dog in the Night-Time has gone on to win seven Olivier Awards, is touring the UK and Ireland, and the Tony Award-winning Broadway production is taking New York by storm. The story is told by a 15-year-old boy who finds other people frightening and confusing, and it has helped transform our understanding of a neurological condition that affects one in 100 children. Alan Yentob looks at a production interwoven with moving testimony from families on the challenges they face as they live with autism.