Named to the 2020 Hal Clement list and the 2020 ALA Rainbow List **An original young adult novel of the Alien universe** Olivia and her twin sister Viola have been dragged around the universe for as long as they can remember. Their parents, both xenobiologists, are always in high demand for their research into obscure alien biology.Just settled on a new colony world, they discover an alien threat unlike anything they’ve ever seen. And suddenly the sisters’ world is ripped apart. On the run from terrifying aliens, Olivia’s knowledge of xenobiology and determination to protect her sister are her only weapons as the colony collapses into chaos. But then a shocking family secret bursts open—one that’s as horrifying to Olivia as the aliens surrounding them.The creatures infiltrate the rich wildlife on this untouched colony world—and quickly start adapting. Olivia’s going to have to adapt, too, if she’s going to survive… **An Imprint Book** “An electrifying adventure … Olivia and Kora are smart, strong young women, and their romance, born in the midst of unspeakable horror, is believable. … A worthy and terrifying addition to a classic sci-fi/horror franchise.” —Kirkus Reviews“Mira Grant blends gritty science fiction, complex characters, and nail-biting horror in Echo! A spellbinding novel of courage and terror.” —Jonathan Maberry, New York Times–bestselling author of Broken Lands and editor of Bug Hunt