Ai Haibara has a secret: she has been able to see ghosts since she was a child.
Her late older sister, as a ghost, is by Ai Haibara's side every moment of every day. Before long, she meets four clever ghost police officers, and through them learns all sorts of things, such as the secrets a certain self-important great detective has been keeping from her: stories about a squinty-eyed lodger, a cafe waiter, and more.
She once thought that the dead could never come back to life. But the Black Organization seems to be conducting experiments in secret, defying fate in an attempt to break through the boundary between life and death, a boundary no one is allowed to tamper with at will.
Before things become irreversible, Ai Haibara and the ghost comrades by her side are doing everything they can to stop it.
Theme: Death is not the end
