Allen Caine was too young to remember when the Earth had not been a conquered planet, one of many such in the huge and sprawling Rygril empire. But he knew of the legendary black collars, guerrilla warriors trained to the limit of human speed and skill, then turned into nearly superhuman combatants by use of the now-lost backlash drug. Eanh and its former colony worlds had been overwhelmed, but sparks of rebellion still smouldered, and the rebel underground on Eanh had sent Caine on an undercover mission to the former Eanh colony of Plinry, where there was a faint hope that a black collar unit still existed. The underground alone knew of a secret that might be humanity's ace in the hole. And if a remnant of black collar fighters still existed on Plinry, they were the only hope of playing that ace in a final bid for the freedom of humanity.