Tyree Campbell 
The Adventures of Colo Collins and Tama Toledo in Space and Time [EPUB ebook] 
In Love and In Trouble

Out on their first date, high school seniors Colo Collins and Tama Toledo are taken aboard a spaceship and offered the chance to intervene in various events in the Universe. Those interventions grow ever more dangerous. Colo and Tama have to deal with a deadly encounter with Adolf Hitler; with hunters who kill for tusks and fur; with a doctor about to spread an infectious fatal disease; with an organization that steals money from governments; and with an observation post that is about to be crushed on the ocean floor. In the meantime, can they find space and time for love?