Shoot-out at Death Canyon - The Time Travel Chronicles, #3

Time Travel Fact: Guns are not the only, nor the most effective, means of erasing an enemy When Madison and Riley return from medieval England, there's good news and bad. The good? They succeeded in their mission to un-erase a fellow student. The bad? A stowaway from the time period turns up in Maddy's science class, seeking revenge. The medieval assassin tries to worm their way into Maddy's friend group and, with barbed comments and dirty tricks, force her out.
Then they go further and kidnap Lauren, Maddy's best friend, jumping through time and space with her. Maddy and Riley learn that the pair have gone to the wild west of America where cowboys and buffalo roam the plains. So they chase them, through dusty towns and saloons, across landscapes of epic beauty and danger. There's a price on their heads and bounty hunters on their trail. Will Maddy find Lauren and escape the west? Or will she have to shoot it out with the assassin and watch the consequences cascade through the time continuum for 150 years? A high-stakes fast-paced time travel adventure in the Wild West.