Alien. Echo

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...