The Crystal Maze, Channel 4, 8pm
RICHARD Ayoade guides five competitors collectively called The Vikings, because they spend most of their spare time living like the seafaring Scandinavians, on an epic adventure through four fantastical zones – Aztec, Medieval, Industrial and Futuristic. In each zone the team members must tackle physical, skill, mystery and mental challenges to win crystals.

Britain by Bike with Larry & George Lamb, Channel 5, 8pm
THE pair load their bikes on to the Paddington-Penzance sleeper train, and after taking a ferry across the Celtic sea, head to the Isles of Scilly. Star Castle, a fortress on St Mary’s, built in Elizabethan times in the shape of a star, is their bed for the night. The next morning, George discovers the delights of Tresco Abbey Gardens, a world-famous botanical garden, while Larry helps deliver the mail with one of the UK’s last cycling posties. The final day coincides with the World Gig Rowing Championship, which draws rowing teams from as far away as the US.

Gardeners’ World, BBC2, 8pm
IF you’re bored with your back yard and want to make it feel more exotic, this edition is not to be missed. Monty Don visits a Hindu temple in Neasden as the team celebrates South Asian influences on British gardens. The amiable host will learn more about the fusion of Hindu Mandir and north-west London suburbia.

Code 37: Sex Crimes, More4, 9pm
VEERLE Baetens, Michael Pas and Marc Lauwrys star in this Belgian 13-parter screened as part of the Walter strand. It orbits around Chief Inspector Hannah Maes, who starts her new job as head of the Ghent police department; a section that specialises in sexual offences, also known as Code 37s. In episode one, the body of wife and mother Kristien De Vadder is found in a hotel room. Who was behind the one-night stand that proved so fatal?