"As the first official members of the International Microsaur Protection Agency, Danny and Lin thought that they were prepared for anything. They've flown with Tiny-Dactyls, herded Tiny-Stegos, and wrangled Tiny-saurus Rexes. But when the Professor's newly upgraded Expand-o-matic messes up, they end up facing their biggest problem yet... a full-sized Triceratops let loose in the middle of the town's yearly Tomato Festival! Will Danny and Lin be able...

After spotting a miniature pterodactyl, Danny and his best friend Lin encounter a mysterious invention that shrinks them down to the size of a raisin.

Forming a plan to render themselves the best Microsaur sitters ever, Danny and Lin are unexpectedly challenged by a pair of rampaging T-rex twins whose antics complicate a race against time to fix the Professor's wrecked lab before they are kicked out of the Microterium.