Books: An ape or an angel?

The ostensible subject of this intriguing book is Richard Leakey's "third angel": a young Canadian woman dispatched to the Indonesian rainforest to study orang-utans. The author, a US novelist living in Toronto, was worried about our rupture with nature. She wants to know how we can readapt ourselves, and senses that this third angel holds the key.

Orang-utans were virtually ignored by naturalists until Richard Leakey sent Birute Galdikas to the nature reserve of Tanjung Puting in Indonesian Borneo in 1971. He was the most famous scientist in the world, she one of his students - an anthropologist with a mission to study the tree dweller and so to learn more about the origins of human behaviour. Leakey found women particularly adept at this kind of observation. His other angels - Jane Goodall and Dian Fossey - became international heroines.

When the Indonesian government outlawed the use of orang-utans as pets 20-odd years ago, they asked Galdikas and her husband to rehabilitate the confiscated creatures. The husband eventually left, so did the son, but Galdikas stuck with the work, married a Dayak and had two more children. She still writes, lectures and lobbies hard for the protection of the rainforest.

The "follow" is a form of research in which the subject is observed and recorded from a distance. This is what Galdikas's students do to orang- utans, and what Spalding did to Galdikas. The book tells the story of her pursuit of Galdikas both in North America and on three trips to Borneo.

Spalding discovers that Galdikas is not an angel at all, she is a monster. Every time she appears in person, she is rude, arrogant and dysfunctional. The book is a catalogue of the arguments that storm between her team and other fieldworkers, focused on the question of whether a human should act as surrogate mother to an orang-utan. Spalding says new theories "have put Birute out of business", and she has lost her licence to research.

Spalding's detective work uncovers shocking tales of cover-ups, dodgy practice, intimidation and worse. Galdikas might be deeply unpleasant, but she is interesting. Yet Spalding also interweaves her own voyage of self-discovery with the orang-utan stuff. This is dangerous territory for writers. Emotional raw material has to be processed before it is dished up in a book. I wasn't interested at all in Spalding's account of the breakdown of her marriage; I longed for the narrative to return to the baddies.

Towards the end she runs out of things to say about Galdikas, and describes other experiences in the forest, notably with the Dayak guide. She writes perceptively about the politics of eco-tourism and the ecological repercussions of Indonesia's transmigration policy. In both content and style, however, Spalding is inconsistent. Sometimes she veers right off the rails: "Of course we were limited by language, which has given us great access to other humans except when we don't hold it in common." Not a bad sentence for an orang-utan, perhaps.

Like a lot of the best non-fiction at the moment, The Follow is a hybrid: part biography, part autobiography, part travelogue and part ecological musing. The idea at its heart - of following the follower - is brilliant, but it is imperfectly executed.