Phoebe Daring

Phoebe Daring by L. Frank Baum

This is the second of a two-volume series that started with The Daring Twins, a story of how the twins restore their family's lost inheritance with the help of Toby Clark, a teen-age orphan. Toby broke his foot helping the Darings and walks with a limp as we begin this second which features the twin Phoebe. Her brother has gone off to college after the twins graduated high school in the first book.
In this second volume Toby is falsely accused of stealing money and papers belonging to Mrs. Ritchie, a widow who doesn't trust banks and stores her money as well as her papers with her lawyer Judge Ferguson in a locked box that he keeps with other such boxes in a secure cupboard. The orphan Toby has been taken on by the lawyer as a clerk. When the Judge dies and the box goes missing Mrs. Ritchie accuses him of taking her box.
When evidence of the theft shows up at Toby's little shack by the river and he is arrested, Phoebe decides to try to find out who is the real thief in order to free her friend. While it looks like Toby is being framed, the true extent of the situation is much more complex and takes all of Phoebe's resources to uncover the truth.
The book starts slowly and it was almost the middle of the book before I became caught up in the mystery of the stolen box. Baum wrote several girl detective mystery series and if you liked the others you may find this one interesting.