In this X-Men adventure novel, an alien species seeking refuge on Earth pose an extinction-level threat to the planet. Hounded by a warship bent on its destruction, an alien spacecraft crashes to Earth. The X-Men race to the scene to help the aliens, but even though they come in peace, the beings onboard could cause mass death across the globe just by their presence. Now the X-Men face an impossible moral dilemma. These aliens deserve to be defended. But they are, by simple biological makeup, an enemy to life on Earth. Long persecuted for being born different, will the X-Men now protect the innocent-or join with their former foes to destroy an evolutionary menace?

Christopher L. Bennett is the author of the critically acclaimed novel Star Trek: Ex Machina as well as Star Trek Titan: Orion's Hounds, Star Trek: S. C. E. #29-Aftermath, and stories in the anthologies Star Trek: Deep Space Nine-Prophecy and Change, Star Trek: Voyager-Distant Shores and Star Trek: Constellations. X-Men: Watchers on the Walls is his first Marvel-universe work.