Arithmetic of Echoes

Echoes can get you into trouble, when you don't know who's listening. The Velmarn, a cold creature of unimaginable power and reach, basks in the silence of the multiverse. Watching, waiting for the reverberations that will awaken its wrath. Its long-vanquished enemies have hidden for millennia, wary of its return. Now, with humanity's discovery of the cosmos-spanning M-drive, the reclusive aliens ...