Two Ice Age kids are orphaned and left to survive alone in the wild after their parents are killed in a bear attack. Tusk and his sister, Flint, discover ancient cave paintings with a horrific warning and instructions on how to survive a deadly meteor headed their way. Tusk is a natural born leader and believes only he can warn others and lead the clans to the land bridge and the New World. Flint has secrets of her own and a plan with a woolly mammoth to unite the animal kingdom before their world is blown away.
It is very short, everything seems to happen in the span of 2-3 days, not the "months" it's supposed to. I've read it, & listened to the narration. Unfortunately, the narrator is very poor. He has no emotion or inflection; his recitation makes the characters more flat & 1 dimensional than they are written.
To the writer: this is a good starting point. Think of this as an outline (you can retire from sales), and build a deeper series off of it. Maybe 10-20 short stories about different trials & tribulations that Tusk & Flint face on their journey!