Edge of the Stars

Siblings Claire and Daniel Stringer are a force to be reckoned with: graduating from Stringer Academy at the top of their respective classes, moving through military ranks at lightning speed, now serving as captain and first mate on the S-Class Cruiser The Legacy. They have recently accepted a mission to locate and capture the military's most wanted criminal. This criminal is responsible for theft of sensitive research documentation and materials relating to an element named Stranteium, which is rumored to possess the capability of opening portals to alternate universes...
Things become difficult for the siblings when they discover the identity of their target is their father, whom they assumed died after going missing 10 years prior. The situation worsens as they learn their father's true motive behind his actions: to find a universe where their mother lived and he died in her place. The siblings will be forced to make a choice: Will they allow their father to achieve his ultimate goal and live as a happy family once more? Or will they put a stop to his plan and save countless universes from destruction?