The Chicago transit system is the nexus of two 

seemingly unconnected murders in Tiffany Cates’s unsettling, satisfying novel M-Theory.

    Donovan rides the train every day, taking note of the different people whom he sees on a regular basis. One day, he begins seeing a woman in a blue coat, Emily (called M by those close to her). He can’t get her off of his mind. The two soon start a relationship that may be just a step up from strangers on a train—or, as Donovan hopes, something much more intimate.

    But Donovan isn’t the only one M has made an impression on during her daily commute. An artist with a generous spirit and a need for connection, M has befriended a number of passengers and transit workers. She searches for meaning in her life, which is marked by a lonely marriage and uncertainty about the future. When a boy M knows is murdered, and M is found dead shortly after, it falls to a detective to put the pieces together and find out how the cases connect.

    Alternating between characters, as well as between the past and the present, M-Theory is a thrill ride that is never quite what it seems. Its events and characters converge in surprising, unsettling ways, illuminating a spider’s web of interdependence that leads to violence.

    As each character deepens, it becomes obvious that no one is truly good or bad; instead, they are all complex and human. Their motivations and actions ring true based on their pasts and personalities, yet there is still plenty of mystery surrounding what they will do next. The climax brings all of the novel’s threads together in a way that is satisfying, but that still leaves room for interpretation. M-Theory is a tension-filled novel that provides no easy answers. ~Angela McQuay

Tiffany Cates writes about Chicago and its citizens with deep respect and consideration, and is able to reveal both their nature and their bonds to one another in the same manner as Stuart Dybek in The Coast of Chicago. Which is to say, Cates captures the spirit and emotional intelligence of us all.
Using noir and romance elements Cates is able to create a sharp, fast-paced, and nuanced page-turner that articulates the complexities of those with and without power. Readers of this well-plotted, stylish prose will be floored by how close each characters' motivations hits to home; how intelligent, how entertaining, how resonant. 
A truly satisfying reading experience, the success of Gillian Flynn, Paula Hawkins, and Stephen King’s books are just a few examples of the large mainstream audience for this type of eerie, haunting—while highly accessible and entertaining—fiction. 
M-theory is made all the richer and more addictive by its intricate storyline and utterly convincing emotional logic.