In Dade County, Florida, disgruntled taxpayer Harry Kee angrily protests a huge IRS bill by wiring up a box of explosives and hijacking a school bus full of special-needs children. Although the kids are terrified, Marta Caldwell, the bus' Cuban-born driver, remains calm and collected throughout the ordeal, not only helping her charges survive the crisis, but also providing comfort and support to a teacher's aide on the verge of a diabetic seizure. But while Marta keeps her head about her, the kidnapper grows more and more unhinged, and the police surround the hijacked bus, ready to shoot to kill if necessary.