The impersonator

From amazon dot com: "In 1917, Jessie Carr, fourteen years old and sole heiress to her family's vast fortune, disappeared without a trace. Now, years later, her uncle Oliver Beckett thinks he's found her: a young actress in a vaudeville playhouse is a dead ringer for his missing niece. But when Oliver confronts the girl, he learns he's wrong. Orphaned young, Leah's been acting since she was a toddler.

Oliver, never one to miss an opportunity, makes a proposition―with his coaching, Leah can impersonate Jessie, claim the fortune, and split it with him. The role of a lifetime, he says. A one-way ticket to Sing Sing, she hears. But when she's let go from her job, Oliver's offer looks a lot more appealing. Leah agrees to the con, but secretly promises herself to try and find out what happened to the real Jessie. There's only one problem: Leah's act won't fool the one person who knows the truth about Jessie's disappearance."