In March 1971, Terence McKenna, his brother Dennis and a small gypsy-like band of friends set off for the Colombian Amazonas. Along the surreal way, they encounter a cast of remarkable characters - including a mushroom, a flying saucer, pirates from outer space, and James Joyce in the guise of poultry.

One result of their adventures was McKenna's theory that psilocybin, the psychoactive ingredient in the stropharia cubensis mushroom, is the missing link in the development of human consciousness and language...