Great gumshoe Daisy Diamond and her best friend, scientist Sally Sosmart, are determined to find the Rising Star Ruby and uncover the culprit who stole it. Now the question is: Are Daisy and Sally smart enough to outsmart this criminal mastermind?

A note left in a book owned by Sally's late aunt leads her and her best friend, Daisy Diamond, to her mansion in search of a priceless artifact. The only problem is, all of Aunt Melvinia's belongings are about to go up for auction the following day, so not only are the girls in a race against time, but also they soon learn they're not the only ones looking for the prized possession.