Occupy Me by Tricia Sullivan

An angelic, high-energy being working behind the scenes to make the world better is drawn into a frantic chase for a stolen briefcase that is actually a gateway to a higher-dimensional realm. The case is in the grasp of a doctor unwillingly possessed by a predatory will tied to an oil conglomerate, and their collision turns into a reality-warping pursuit through city streets, aircraft, and impossible spaces where time slips and prehistoric creatures intrude. As identities blur and physics unravels, she must confront the parasitic intelligence and reclaim the device before it reshapes the future.

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