On the Road With Mallory (Mallory McDonald, Bk. 25)

Mallory has a new journal, just in time for her family's vacation to the Grand Canyon. She can't wait for the road trip—until it turns out that her cousin, Kate, is coming along. Kate would rather read a list of "fun facts" than have actual fun at the amazing stops along the route. And when Kate catches Max texting a mysterious girl, the backseat of the minivan starts to seem like the last place Mallory wants to be. With everyone arguing and keeping secrets, can Mallory somehow save the trip?