Dr Mark Powell (Bridges) is reluctant to dismiss mild-mannered 'Prot' (Spacey) - who claims to be a visitor from the planet K-PAX - as the incurable loony diagnosed by his colleagues at the Psychiatric Institute of Manhattan. For one thing, Prot is logical, and his knowledge of the cosmos rivals top boffins; for another, he has an uncanny ability to calm and help the institute's other inmates. But could he really be an alien? And if not, who is he? Softley and his stars invest this mystery with more respect than it deserves. Since Charles Leavitt's adaptation of Gene Brewer's book can never decide whether Prot's a starman, madman or Messiah, the film steadily turns into a murky mélange of banal explanation, far-fetched wish fulfilment and moralistic metaphor. The Oliver Sacks-lite psychiatric seasoning simply sours the brew.