The fun fourth space opera in Holmes’s Stars Edge series (after Strangers) takes rough-edged heroine Nel Bently back to Earth in search of the source of a deadly audio signal. After the explosive events on Samsara in the previous installment, Nel isn’t on the best of terms with the ruling superpower, IDH. Its members don’t trust her, and she doesn’t trust them—not even her maybe girlfriend, Lin Nalawangsa, an IDH lieutenant. On Earth, Nel uses her skills as an archaeologist to unearth clues that could lead to the source of the audio signal and its creator. Along the way, she discovers hazardous, and familiar, technology that makes her question the IDH’s role on Earth and the purpose of her mission. Now caught between the IDH and a dangerous Earth group known as the Founders, Nel finds herself under threat yet again. Though the action is a bit slow to start, once it revs up it’s delightful. Holmes blends archaeology and science fiction into a unique romp that’s sure to be a hit with series fans.