Second in a series of books updating the Clasic Traveller Alien Modules to the MegaTraveller rules set and the Rebelleon era. The two races presented here are given a full treatment, covering history, physiology, culture, psychology and technology. Starmaps are also included, as well as expanded character creation rules in the MegaTraveller format. The overall level and quality of detail is much higher than in the Classic Traveller Alien Modules 1 and 6, the original detailed presentation of the Solomani and Aslan. The Solomani (humans from Sol; i. e. our own star system,) are especially important to the Traveller setting.

Five books were to be published in this series, but only one other, The MegaTraveller Alien, Volume 1: Vilani & Vargr, was actually published. The other three were to cover the Zhodani and Droyne (Volume 3,) the K'kree and Hivers (Volume 4,) and various other minor races, both human and inhuman (in Volume 5.)

Traveller fans sometimes refer to this book as "Rats & Cats" as a setting in-joke.