As the novel begins, nine-year-old Jommy Cross (a telepathic Slan of the first type) travels with his mother to the capital, Centropolis.

Jommy Cross is not only the heir to the brilliant inventions of his father, but he represents the last hope of the Slan race to save it from genocide.

"[3] In a back-cover blurb in the 1998 Orb edition, Charles de Lint says this: "Over fifty years on from when it first saw print, van Vogt's Slan is still one of the quintessential classics in the field that other SF novels will inevitably be measured against."

"[4] In American science fiction fandom, the slogan "Fans are slans"[5][6] quickly developed, making the analogy between science fiction fans, perceived as harassed because of their greater intelligence and imaginative capacity, and the slans in the novel, who are persecuted for their superior mental abilities.

The first Slan Shack to bear that name was established in 1943 in Battle Creek, Michigan by Al and Abby Lou Ashley, Walt Liebscher, E. Everett Evans and fan artist Jack Wiedenbeck.

Both stories feature a hero named Jommy/Jomy, who discovers that he is a member of a race of telepathic mutants, who are persecuted by artificial general intelligence and non-telepathic humans[9] brainwashed by them.