Having thwarted Bowser's previous plot to marry Princess Peach, Mario and Luigi now face a fresh threat in Bowser Jr., who is determined to liberate his father from captivity and restore the family legacy. Alongside companions new and old, the brothers travel across the stars to stop the young heir's crusade.

Astronaut Ryland Grace awakens on a spacecraft with no memory of himself or his mission. He slowly deduces he is the sole survivor of a crew sent to the Tau Ceti solar system in search of a solution to a catastrophic event on Earth. In his search for answers, Grace must rely on his vast array of scientific knowledge, sheer ingenuity, and human will – but he may not have to search alone.