Robert Silverberg 
Starhaven 

After years of beachcombing on the pleasure planet of Mulciber, ex-engineer Johnny Mantell thought he had hit rock bottom. But when he was unjustly accused of murder, he knew there was worse to come. Johnny had to get out. And the only place for an outcast like himself was the impregnable outlaw world of Starhaven, a refuge that defied all galactic laws.Once there, Johnny’s only wish was to forget the past and be left alone. But the super-science dictator of Starhaven had other plans for him. And soon Johnny found himself in the midst of one of the most explosive struggles the world had ever known. If he failed, not only his own life would be lost, but the future of galactic civilisation would be totally altered.