Five people with an extreme fear of heights set off on a once-in-a lifetime adventure to cure their debilitating phobia. Accompanied by presenter Mel Giedroyc, the five sufferers confront their fears head-on as they undergo exposure therapy. From the dramatic peaks of the Alps to the world's tallest building, they'll attempt a series of increasingly difficult height-based challenges that will push them to their limits. Can they rise to the challenge and develop a head for heights? Shot in stunning locations in the UK, Austria, Switzerland, Abu Dhabi and Dubai, the show climaxes at the tallest building in the world - the 828m Burj Khalifa tower. It's almost twice the height of London's Shard - will the five phobics be able to overcome their fear and climb it, or will it be mission impossible? Presenter Mel Giedroyc is joined by Oxford University psychologist Dr Jennifer Wild as they lead the group on this hair-raising and life-changing journey.