Forensic geologist Em Hansen has barely survived a series of life-altering events that have forced her to get to know herself all over again. Her long-time boyfriend is now a few months in her past, the future she had laid out for herself has evaporated into thin air, and her new man, Jack Sampler, has run away. Well, not run away, exactly, but has set off on a secret operation, possibly related to his job as an FBI agent, without telling Em where he is going or when he'll be back.

It soon becomes dear that he's in Florida, perhaps as part of an investigation the FBI has been running on a cloud of dust moving into the atmosphere, ostensibly borne on winds from Africa, and the implications it has for global politics. But Em suspects something more sinister may be at work. Will Jack ever forgive her for following him to the southeast and butting in on his case? That is, if they ever get out of this situation with their relationship, not to mention their bodies, intact.