In London, the sideshow troupe of Doctor Parnassus promises to the audiences a journey to the "Imaginarium", an imaginary world commanded by the mind of Doctor Parnassus where dreams come true. In the stories that Doctor Parnassus tells to his daughter Valentina, to the midget Percy, and his assistant Anton, he claims to have more than one thousand years; however, when he felt in love for a mortal, he made a deal with the devil Mr. Nick trading his immortality per youth. As part of the bargain, he promised his son or daughter to Mr. Nick on the sixteenth birthday. Valentina now is almost in the doomed age and Doctor Parnassus bets with Mr. Nick that whoever seduces five souls in the Imaginarium will have Valentina as a prize. Meanwhile the troupe rescues Tony that was hanged on a bridge by the Russians that explains why he had been chased and he joins the group. Tony and Valentina fall in love for each other and the jealous Anton discovers that his competitor is a liar.