Jake The Time Jumper. The Portal Walker Series, #1

A glitch in time. A vanished sister. And a prehistoric world where the future hangs in the balance. Young coding prodigy Jake Parker never expected a normal day to end in disaster. But when a rogue time rift pulls him into a violent, untamed past, survival becomes his only goal. Separated from his sister Emma, stripped of his tech, and stalked by predators both human and wild, Jake must rely on instinct-and the unlikely help of Amna, a fierce tribal leader who's as suspicious as she is brave.
But time travel comes with consequences. As Jake navigates the dangers of a world untouched by civilization, he begins to unravel a mystery bigger than survival: a lost artifact with the power to bend time itself, strange memories that don't belong to him, and the possibility that Emma made it through the rift first-and may have already changed history. Now, Jake must piece together the truth before the timeline fractures for good.
Because the key to going home might not be hacking the system..it might be rewriting it. Perfect for fans of The Maze Runner, Dark Matter, and The Marrow Thieves, this action-packed YA sci-fi adventure explores survival, identity, and the secrets that shape our future-and our past.