The Violin by Odella Howe:
 
When Elise’s fiancé dies, she would do anything to get him back—even if that means striking a sinister bargain with Cassius McCalmont, an exotic collector whose oddity exhibit is downright astonishing.

After seeing Cassius’s otherworldly flute work its magic, Elise begs her father for an apprenticeship, eager to make the seemingly simple sacrifice required to bring her beloved back from the give Cassius a violin of her own making.

But before she can finish, Elise’s father falls deathly ill. Even Cassius’s elixirs can’t restore his health for long, and her father’s dying wish may very well be Elise’s undoing.

Now she faces a grim obey her father and let him pass in peace, or trust the man who promises her power over the grave.