Almost everyone has irrational fears - of mice, aeroplanes, dogs, sex, spiders, or the dark ... But, for some, these fears are crippling. Drugs and psychotherapy often help, but all anxiety states are very difficult to cure completely. In the last few years a growing number of people have been treated with a relatively new technique: behaviour therapy. It's vehemently attacked by its critics for being simplistic and reducing the status of human behaviour to that of laboratory rats. But its supporters claim that it's more rational in theory and more effective in practice than traditional techniques. Nick Ross follows and talks to three people as they try this treatment for fear.