I was going to suggest that this book is not for the faint hearted; on further reflection perhaps the faint hearted are precisely who the book is for. It's a novel which has already divided the American critics. Michiko Kakutani in the International Herald Tribune has gone so far as to suggest that if it hadn't been written by Alice Walker it probably wouldn't have been published, dismissing it as "a remarkably awful compendium of inanities". Walker's supporters praise the novel's intricacy, its mix of magic and parables, repressed memories and dreams. One thing is for sure. Nobody who makes it to Chapter One will be able to claim they hadn't been warned about what they were letting themselves in for. Walker opens by expressing her gratitude "to all devas, angels, and bodhisattvas who accompany, watch over and protect explorers, pioneers, and artists". This is followed by an epigraph from Winnie Mandela: "So far, there is no law against dreaming." The final hurdle is the dedication to her father's murdered mother: "a memorial to the psychic explorer she might have become."

If, having got through all of this New Age preamble, you don't feel tempted to slide the book politely back into the clutches of Walker's earlier prize–winning efforts such as The Color Purple, you'll perhaps be the kind of reader who allows a sympathetic smile when you encounter the novel's protagonist. We meet Kate meditating in a large hall surrounded by trees. She's the only "person of colour" at the retreat and we're told that since she was a child she had felt a "wary futility about talking". Her previous surname was Nelson but she wanted a change. For a while she thought of calling herself Kate Nelson–Fir because she loved trees (as a child she was a literal tree–hugger). She finally, some would say inadvisedly, plumped for 'Talkingtree'.

As the name change suggests, 57–year old Kate's a bit out of sorts. Her knees have started creaking. She's a published writer and to some extent a public figure, but she feels anonymous, weary and "unconvinced of the need to do anything further with her life". She's taken to burning $100 bills and is troubled by dreams about dry rivers. Concerned friends, "the ones in her psyche and the ones sitting around her dining table", advise her to go off and find a real one.

Her partner, Yolo, isn't invited to go with her. Kate hasn't married Yolo — which comes as something of a surprise to the reader since she must be the most married character in literature. Walker tells us that, like Elizabeth Taylor, Talkingtree had been married many times. How many times is not made clear, but three apparently lasted about a year, some were short lived, the others, one in which she had borne children, were longer. The vagueness of 'some' and 'others' suggests the tally could be around eleven or twelve, possibly even higher. Small wonder she needs a break from men.

On an all–women river trip down the Colorado, she finds herself throwing up. This is not, as you might expect, provoked by the motion of the small boat through the rapids. It's Kate purging herself of the memories of an earlier marriage, more particularly the white daisies that decorated a serving dish her husband bought her one Valentine's Day. "It was these flowers, dozens of them, that now poured from her mouth. At the time of the gift she'd stuffed her disappointment." But she now saw it as symbolic: she had entered the unromantic period of her life, and because her daughter had helped her father choose the dish, she was in cahoots with him. A double betrayal.

The Colorado trip doesn't do the job of healing her. In search of stronger medicine she sets out along the Amazon and is dropped off in the jungle with a group of other medicine seekers. For two weeks, under the guidance of Armando, a Shaman, and Cosmi, who accompanies him on a reed flute, they take a powerful hallucinogenic called yagé. Here Kate meets Missy who's been "incested" by her grandfather, a clown who gave up clowning around because his heart wasn't in it. There's also Lalika, a woman who murdered the man who raped her, and was then serially raped in prison. Rick, a drug dealer, is another confidant. Under the influence of yagé Rick has the unsettling habit of pretending to be an orang–utan. Over the course of a fortnight the group come face to face, and in some cases to terms with, their demons and tormentors.

Meanwhile, Yolo's also on a journey. His takes him to Hawaii where he encounters a corpse, an old girlfriend, and two Aborigines "from Australia" who confide an addiction to petrol sniffing. While the Amazon group get stoned in an attempt to commune with their pasts, the Aborigines tell Yolo they used petrol fumes to enter a fake Dreamtime; to help them forget that once upon a time they were at one with the land and the sea.

The question that hangs over this novel, and indeed has to carry almost all of the narrative interest, is whether Yolo and Talkingtree will get back together once their respective journeys are over. Frankly, it's hard to care. Alice Walker has written a book about dreams, but the dreams of others are, by and large, fairly tedious. Removed from the scaffolding of experience they tend towards collapsing into meaninglessness.

Now is the time to open your heart is available from Amazon (UK)