Hidden Empire is the first of Kevin J. Anderson’s The Saga of the Seven Suns. In this universe humans live alongside one
alien race and know of one no longer extant race. A pair of archeologists find a tool the Klikiss (the extinct
race) used to ignite gas planets into small suns and use the tool on such a
planet. Unfortunately it turns out that
a vastly superior race of hydrogen based aliens have colonized such giant gas
planets throughout the galaxy so the experiment results in a local genocide and
sets up a war between humans & Ildirans and the unsuspected hydrogues. Much of this book is spent setting up this
scenario. The book has a large number
of characters spread across the galaxy and switches viewpoints between them to
keep a lot of plot threads going. The
book ends on a cliff hanger with many of the principal characters in peril of
one sort or another…. You’re clearly supposed to continue the series.