Horizon: Madagascar - A Treetop Odyssey (BBC2)

UFOs: The Secret Evidence (C4)

THE scene resembled something from a fantasy film as a gaily-coloured hot air balloon landed the giant pretzel suspended beneath it on to the canopy of the Madagascar rainforest.

The pretzel was the nickname given to the specially designed 400 square metre raft that "floated" on the top of the trees. A metal tree house was lowered between branches to make an observation point, and a scientist attached to a mini-hot air balloon floated over the trees gathering specimens.

Extreme solutions were needed to explore 40 metres above the ground in one of the most untouched rainforests in the world. It's home to rare plants and animals, 75 per cent of which are found nowhere else on earth.

Reaching them is difficult. Until now, the forest canopy has been inaccessible to scientists. Hence the need for the pretzel, enabling them to walk about on the top of the trees ten storeys or more above the ground.

There was a reason other than scientific curiosity for the three-month expedition. They had high hopes - an appropriate phrase considering the height at which they worked - of finding ways to protect the rainforest from further deforestation.

The team included botanists, frog experts, perfume experts and even someone seeking new kinds of fruits to use in sorbets and ice cream. Their aim was to find plants and creatures for use in the pharmaceutical, perfume and flavouring industries. If they could find commercial uses for the forest's inhabitants, politicians and economists might be persuaded to stop destroying the forest.

The serious purpose didn't stop them getting excited at their finds, whether it was a moth cocoon, a chameleon smaller than a caterpillar or a new species of frog.

We also learnt about the sex life of liana, a vine that gets everywhere. The expert couldn't find the bottom (always a problem, I find) because it can live without a trunk. Professor Francis Halle declared it was "very active up above" with "considerable leaf surface and enormous sexual activity because liana are plants with an overabundance of flowers". Sounds like a visit to a sex addiction clinic is in order.

Defence journalist Nick Cook was also concerned with things up high in UFOs: The Secret Evidence, an exhaustive investigation into flying saucers and alien sightings.

This was all fascinating stuff as he sought the low-down on stories most of us only half know. The earliest UFO sightings came during the Second World War, with one pilot describing a "screaming dogfight with strange balls of light".

Cook's tour took in the Roswell incident, Cold War misinformation, and all manner of UFOs. Travis Walton, billed as the first alien abductee, described in convincing detail what happened to him.

Cook found possible explanations for most things - experimental aircraft, strange cloud formations, disc-shaped cars and a supersonic saucer.

As much as you feel you ought to dismiss them as flights of fancy, something at the back of your mind makes you wish there's some truth in them and that something is out there. Just as long as it's friendly