The Devil's Nebula

Ed Carew and his small ragtag crew are smugglers and ne'er-do- wells,
thumbing their noses at the Expansion, the vast human hegemony
extending across thousands of worlds... until the day they are caught,
and offered a choice between working for the Expansion and an
ignominious death. They must trespass across the domain of humanity's
neighbours, the Vetch - the inscrutable alien race with whom humanity
has warred, at terrible cost of life, and only recently arrived at an
uneasy peace - and into uncharted space beyond, among the strange worlds
of the Devil's Nebula, looking for long-lost settlers.

A new evil threatens not only the Expansion itself, but the Vetch as
well. In the long run, the survival of both races may depend on their
ability to lay aside their differences and co-operate.