A completely broken time machine is about to cause the ultimate historical disaster. When a simple attempt to fix their malfunctioning device goes horribly wrong, Liam and his brilliant friend Elsa find themselves tumbling wildly out of control through the absolute deepest layers of human history. Instead of landing in a helpful past century, they are violently thrown all the way back to the incredibly dangerous dawn of time. Surviving prehistoric environments and dodging massive, hungry creatures is only the very first part of their massive problem. The very fabric of the timeline is beginning to physically unravel right before their eyes, and they are the only ones equipped to patch it up. To finally get back home and rescue their trapped parents, these two resourceful fifth graders must outsmart ancient threats, invent clever new gadgets out of absolutely nothing, and hold onto their sense of humor while racing against history itself.