Moonshadow, as an old man, narrates his life as a youth, beginning with Blake's Songs of Innocence and Experience.
He begins by describing the history of the G'L-Doses, a powerful, inexplicable alien race of glowing balls with smiley faces. They are known for both destroying and saving civilizations across the cosmos, according to their whim. One day they bring the hippie human Sunflower to their Zoo. A G'L-Doses marries her and they have a child, Moonshadow, who grows into his teens as a thorough Romantic, full of daydreams of women and swordplay from his constant reading.
In the Zoo he meets Ira, a scurrilous, prurient cynic who despises Moon's innocence. Moon is infatuated, however, and constantly follows him around, buying his companionship with intergalactic porn from his library.
One day, Moon's alien father shows up and pronounces that it is time for him to leave the Zoo, along with his mother, their cat Frodo, and Ira. They are all promptly teleported to a spaceship, the Decrepit. Moon is overjoyed at the chance to make his Romantic dreams of adventure come alive, and captains the ship into space...while Ira is far less excited at leaving the numbing comfort of the Zoo.