Unexplained disappearances of families shake Chicagoland as evidence left at each scene points to the possibility of extraterrestrial abduction. Lieutenant Kerry O'Malley leads Chicago's Crime Scene Investigation team in poring over the evidence left in these cases and sticking to the facts amidst alien abduction media hype. When the kidnappings are finally pinned on a wealthy Choice system tech mogul, the team launches a manhunt. Meanwhile, many of the abductees are returned seemingly unharmed. Monitoring the behavior of the abductees while searching for the perpetrator, Kerry's CSIs find themselves witnesses to an incredibly complex plot that unfolds before they can fully understand it, much less hope to stop it. When Kerry becomes a target herself, she discovers the dangerous capabilities of the Choice system in the wrong hands, and her world view and career are forever impacted.