25 for set in paperback ) The Saga of the Pliocene Exile , a title I couldn ' t resist , begins in the not - toodistant future when ... Our story follows the eight Exiles of Group Green as they travel from 2110 A . D . to encounter the Pliocene . ... for Viking adventures finds no legal outlet in the modern world ; Aiken Drum , the " natural crook " and practical joker whose ... The plot is outlined in the first book of the series , which also documents the beginning of the human revolt against the Tanu .