Princess Magnolia is excited to go to the Science Fair to present her poster about seeds and plants.

But when she and her friends arrive they find a surprise goo monster at the fair.

This is a job for the Princess in Black and the Princess in Blankets!

But will two masked heroes be enough to save the science fair?

A little scientific problem-solving – and a lot of princess power – will make the sixth entry in the New York Times best-selling series a smash hit.