Penny Nichols and the Mystery of the Lost Key

Penny Nichols is the daughter of Christopher Nichols, a successful detective. Mr. Nichols often scoffs at Penny\'s ideas, but when Penny is proved to be right, Mr. Nichols has to admit that Penny has the makings of a good detective. Penny\'s best friend is Susan Altman, and Susan usually accompanies Penny in her adventures.

Penny\'s generosity and unbounded friendliness earn her an instant friend in Rosanna Winters, a young lady in need of advice. Rosanna has inherited the property of her late uncle, Jacob Winters, and must inspect the estate at her earliest convenience. Penny suspects that Rosanna may be the victim of a hoax.
Nevertheless, Penny agrees to accompany Rosanna to the Winters home. Upon their arrival, the girls discover two additional claimants to the estate, each of whom with a letter from Mr. Winters\' lawyer! Most troubling, Rosanna\'s letter has disappeared, leaving her no claim!

Can Penny help Rosanna, and find out the truth?