The Cult Next Door (BBC2, regions vary)

THE extraordinary story of a strange cult that came to light in 2013, when three women emerged from a small flat in Brixton, south London, after decades in captivity. The documentary traces the group back to its roots in the 1970s, when Aravindan Balakrishnan, who believed in an international communist revolution, created a tiny political sect that followed the teachings of China's Chairman Mao. However, his left-wing collective evolved into a pseudo-religious cult, in which members were controlled, threatened and brainwashed so that they were too terrified to leave.

Tracing the group back to its roots in the 1970s, the one-off biopic by film-maker Vanessa Engle describes how its leader, Aravindan Balakrishnan (who was jailed last year for 23 years), then a student of Indian origin, believed in an international communist revolution and created a tiny political sect that followed the teachings of China's Chairman Mao.

But how did this evolve into a bizarre pseudo-religious cult, where members were controlled, threatened and brainwashed so that they were too terrified to leave? (Balakrishnan's convictions included rape charges, too.)

With exclusive interviews, unprecedented archive access and a filming window at the "scene of the crime", Engle feels her documentary is must-watch...

"I felt very strongly that it was for me," says Engle. "And the reason I felt that was because I had made the series Lefties in Villa Road, a squatters' street in Brixton, which is literally about 20 yards from where the collective ended up.

"So when I started making the film, I felt like I had already covered that territory of what was going on in Brixton at that time."

But nothing would prepare her for just how "strange and unfathomable" the narrative would be.

Spy in the Wild (BBC1, 8pm)

THE undercover cameras reveal how animals rely upon each other for a range of activities. Arctic wolves group together to survive in one of the harshest landscapes on earth, a band of hungry mongoose groom warthogs for tasty morsels - before turning their attention to Spy Warthog - and fish help clean hippos' bodies, as well as providing a unique dental service. Meanwhile, crocodiles and dikkop birds take part in a mutual neighbourhood watch against hungry prowling monitor lizards, and Spy Rattlesnake captures how prairie dogs and burrowing owls use their language skills to tell the rest of their community of approaching danger.

Death in Paradise (BBC1, 9pm)

IF you want further proof that Saint Marie is a dangerous place to live, even the island's cricket club's 'friendly' fixtures end in murder. The team have won a testimonial match against their local rivals, but the celebrations are cut short when Saint Marie's club president Jerome Martin is found shot dead in the middle of the cricket pitch. Suspicion immediately falls on his family and fellow teammates, but as so often is the case in Death in Paradise, everyone appears to have a cast-iron alibi. There's another mystery brewing as JP senses that Dwayne is hiding something from him, while Humphrey faces up to the prospect of life without Martha as her final day on the island looms ever closer.

Spies (C4, 9pm)

AS we reach the end of the series, six trainees remain on the course, but only four can make it through to the final, solo test. This last challenge, which involves a mission in Marrakech, has been designed to recreate the conditions a genuine intelligence officer might face in hostile conditions. On arrival, the trainees must hand their passports to an unknown contact and use their alias documents to check into a hotel, all while acting 'normally'. However, unbeknownst to them, they can't even relax behind closed doors as their hotel rooms have been rigged with cameras to observe how they deal with the pressure. One candidate is already struggling to keep it together and things are only about to get worse as the trainees are 'arrested' and subjected to a hostile interview under extreme conditions. By this point only three remain, but who will emerge as the best potential spy?

Viv Hardwick