Helix Wars by Eric Brown

SPIRAL INTO WAR! The Helix: a vast spiral of ten thousand worlds turning around its sun. Aeons ago, the enigmatic Builders constructed the Helix as a refuge for alien races on the verge of extinction. Two hundred years ago, humankind came to the Helix aboard a great colony ship, and the builders conferred on them the mantle of peacekeepers. For that long, peace has reigned on the Helix. But when shuttle pilot Jeff Ellis crash-lands on the world of Phandra, he interrupts a barbarous invasion from the neighbouring Sporelli, who are now racing to catch and exterminate Ellis before he can return to New Earth and inform the peacekeepers. Eric Brown returns to the rich worlds he created in the best-selling Helix with a vast science-fiction adventure populated with strange characters and fascinating creatures.