Paul Barnett: Strider’s Universe [1998] paperback

Captain Leonie Strider and the crew of the Santa Maria, stranded in a galaxy millions of parsecs from Earth, have helped the species of the Wondervale to defeat the tyrant Autarch Nalla. But all too soon the remaining warlords are in-fighting. Only Strider and a handful of crewmates elect to remain in the Wondervale to help, but first she must overcome an even older danger that threatens to destroy them all.