The Mysterious Case of the Missing Ghost

Emily Hildebrandt is learning to settle into some of the very strange cases that come through The Redemption Detective Agency's door.
Like Aunt Tilde's friend Ruth who claims she's lost a ghost.
How does one lose a ghost? Apparently when the ghost decides to walk out the door.
But, to make matters more complicated, it's not just any ghost but the ghost of Ruth's dead husband. Who was murdered decades ago under very suspicious circumstances.
Emily has no choice but to go back in time and figure out what really happened to Ruth's husband, in order for everyone to rest in peace.