Ruby Young's new Boston apartment comes with all the usual perks. Windows facing the brick wall of the next-door building. Heat that barely works. A malfunctioning buzzer. Noisy neighbours. A dead body on the sidewalk outside. And of course, a ghost.

Since Cordelia Graves died in her apartment a few months ago, she's kept up her residency, despite being bored out of her (non-tangible) skull and frustrated by her new roommate. When her across-the-hall neighbour, Jake Macintyre, is shot and killed in an apparent mugging gone wrong outside their building, Cordelia is convinced there’s more to it and is determined to bring his killer to justice.

Unfortunately, Cordelia, being dead herself, can't solve the mystery alone. She has to enlist the help of the obnoxiously perky, living tenant of her apartment. Ruby is twenty, annoying, and has never met a houseplant she couldn't kill. But she also can do everything Cordelia can't, from interviewing suspects to researching Jake on the library computers that go up in a puff of smoke if Cordelia gets too close. As the roommates form an unlikely friendship and get closer to the truth about Jake's death, they also start to uncover other dangerous secrets.