The first book in a hard science fiction series about a female biologist who must protect the human race after a devastating alien invasion . . .

Dr. Mackenzie “Mac” Connor is a workaholic and trained biologist at the Norcoast Salmon Research Facility. When she and fellow scientist Dr. Emily Mamani settle in to monitor this year’s salmon runs, an unprecedented arrival interrupts their research: Brymn, an archaeologist and the first Ohryn alien to ever set foot on Earth. He has come to get Mac’s help in uncovering what created the Chasm—a part of the universe whose once-populated worlds are now mysteriously empty of any life-forms.

When a devastating attack on the Base results in Emily’s abduction, Mac is forced to flee with Brymn—and to wonder if Earth may be under attack by the Ro, the aliens Brymn suspects are behind the Chasm. Cut off from everything and everyone she knows, Mac finds herself in grave danger and charged with protecting the human race from extinction...

In this first novel in the Species Imperative science fiction series, biologist and author Julie E. Czerneda creates a stunning cast of characters, both alien and human, and a universe which will draw readers into a magnificent tale of interstellar intrigue.