Big Blue Live (BBC1, 7pm)
In the final visit to Monterey Bay, the team is on the lookout for blue whales - which prove surprisingly difficult to locate despite their huge size.
Steve Backshall takes to the air in an attempt to spot them, while Liz Bonnin joins scientists trying to tag the animals.
Matt Baker examines a sea otter’s role in maintaining the ecosystem, Hugh Fearnley-Whittingstall reveals how shipping companies try to avoid collisions between ships and whales, and twitchers will be happy to see sooty shearwaters flying in from New Zealand.
Animal Mums (UTV, 7pm)
The series looking at how animals raise their young continues tonight with a look at how some species will work together to look after all the youngsters in a social group.
The programme also features a lioness with eight boisterous cubs, and speaks to sheep farmers, who reveal how lambs have the ability pick their mothers’ voices out of the crowd.
Plus, insights into how gannets and seals manage to find their way back to their offspring after hunting for food, and a demonstration of bad behaviour among young goats and orangutans.
The X Factor (TV3, 8pm)
X Factor veterans Simon Cowell and Cheryl Fernandez-Versin are back to pave the way for new recruits, pop sensation Rita Ora and much-loved radio DJ Nick Grimshaw.
Our favourite Xtra Factor duo, Olly Murs and Caroline Flack are making their return but this time it's for the main show.
The new series will also see the auditions move out of the rooms and straight into the arenas, with hopefuls having to perform in front of an arena audience from the start in the hope of making it through to the next stage.
Time Crashers (Ch4, 8pm)
Tony Robinson gives celebrity time travellers Kirstie Alley, Fern Britton, Louise Minchin, Zoe Smith, Meg Mathews, Keith Allen, Greg Rutherford, Charlie Condou, Jermaine Jenas and Chris Ramsey a taste of life in 1468.
They are split into two teams and assigned to work as squires for two knights preparing to face each other in a jousting tournament.
They must take on an assortment of tasks, including mending armour, preparing horses and taking their master’s urine to be checked for diseases by a physician.
The Trials of Jimmy Rose (UTV, 9pm)
Casting Ray Winstone in a TV drama is always a good move – but recruiting his Sexy Beast co-star Amanda Redman to play his estranged wife makes the new three-parter The Trials of Jimmy Rose virtually unmissable.
It follows the eponymous Jimmy (Winstone), an armed robber who has just been released following a 12-year prison sentence.
He’s looking forward to being reunited with his family, but they have much more mixed feelings about having him home, with wife Jackie (Redman) admitting she’s not sure she still loves him.
However, the biggest shock comes when he discovers that his granddaughter Ellie is now a drug addict. Can Jimmy’s quest to find her and get her clean provide a route back into his family?
Partners in Crime (BBC1, 9pm)
Part three of three. Tommy is held captive by the mysterious ’N’ along with Gilbert Worthing, who reveals that he has hidden a vital key that operates the stolen nuclear bomb.
Tuppence comes to the rescue, and together they set out to retrieve the key – but it is hidden in the Sans Souci, where the enemy agent is lying in wait.
The couple enlist Carter’s aid in carrying out an audacious plan to save the lives of thousands of innocent British citizens.
Conclusion of the adventure series based on Agatha Christie’s series of novels. Last in the series.
Special Forces – Ultimate Hell Week (BBC2, 9pm)
Have you got what it takes to make it through some of the world’s toughest military training regimes?
Some viewers will happily reply ’nope’ before putting the kettle on and preparing for a night in front of the TV watching the people who do think they can make the grade.
Presented by cricketing legend Andrew ’Freddie’ Flintoff, Special Forces: Are You Tough Enough sees some of the UK’s fittest men and women putting themselves through the gruelling tests used by the Navy Seals and SAS in a bid to see who is the toughest recruit.
It’s not all about physical strength though, their mental endurance will also be pushed to the limit, as viewers find out what it really takes to be the ultimate soldier.
The Best Exotic Marigold Hotel (Channel 4, 9.00pm)
(2011) Evelyn (Judi Dench) has recently lost her husband and is coming to terms with solitude in her twilight years.
Determined to start anew, she abandons Britain for the balmier climes of Jaipur and a retirement home called The Best Exotic Marigold Hotel.
En route, Evelyn meets other retirees all bound for this “luxury development for residents in their golden years”: cantankerous wheelchair user Muriel (Maggie Smith), waspish snob Jean (Penelope Wilton) and her long-suffering husband Douglas (Bill Nighy); retired judge Graham (Tom Wilkinson); ladies’ man Norman (Ronald Pickup); and spinster Madge (Celia Imrie).
When the travellers arrive at their destination, they discover a building in disrepair and an inexperienced manager, Sonny (Dev Patel), struggling to keep the creditors off his back.
The Xtra Factor 2015 (TV3, 10pm)
TV Presenter and KISS FM Radio DJ, Melvin Odoom and popstar and TV presenter, Rochelle Humes will host the popular X Factor sister show - The Xtra Factor.
The new presenting duo will be in the centre of the action, bringing the fun factor to the search to find a new music star.
They will follow the auditions across the country, getting backstage gossip, unveiling unseen footage and getting unprecedented access to The X Factor judges, Cheryl Fernandez-Versini, Nick Grimshaw, Rita Ora and Simon Cowell.
In the Valley of Elah (BBC1, 11.30pm)
(2007) Tommy Lee Jones and Charlize Theron star in this slow-burning thriller inspired by true events.
Shortly after a tour of duty in the Middle East, Specialist Mike Deerfield (Jonathan Tucker) goes AWOL and his gruff father, retired military police officer Hank (Jones), seeks answers from Mike’s superior, Sergeant Carnelli, and military policeman Lieutenant Kirklande.
They seem unconcerned by the boy’s absence, prompting Hank to turn to local cop Detective Emily Sanders (Theron).
When Mike’s charred remains are discovered on wasteland, and the military glosses over the facts, the resourceful father is outraged.
So Hank turns private eye, working alongside Detective Sanders to unearth the truth, which might have been better left dead and buried on the streets of Iraq.
Tom at the Farm (Channel 4, 1.25am)
(2013) Xavier Dolan writes, directs and stars in his third feature, a psychological thriller based on the stage play by Michel Marc Bouchard.
Advertising copywriter Tom (Dolan) ventures from Montreal to the countryside to attend the funeral of his lover Guillaume.
He quickly learns that his boyfriend’s family knew nothing about their relationship and they believe Guillaume had a girlfriend, who is unable to attend the service.
Guillaume’s brother Francis (Pierre-Yves Cardinal) uses intimidation to ensure Tom doesn’t tell the truth to their mother and insists that Tom remains at the farm to play peacekeeper between the various factions.
As Tom becomes mired in the lives of his dysfunctional hosts, he sparks a dangerous, homoerotic attraction to Francis that threatens to destroy everything.