Bill Browning heads the trauma unit at San Francisco's busiest emergency room. With his ex-wife and daughters in London, he immerses himself in his work and lives for the little time he can spend with his children. A rising star at her teaching hospital, Stephanie Lawrence has two young sons, a frustrated stay-at-home husband, and not enough time for any of them. Harvard-educated Wendy Jones is a dedicated trauma doctor, trapped in a dead-end relationship with a married cardiac surgeon. And Tom Wylie's popularity with women rivals the superb medical skills he employs at his medical centre, but he refuses to let anyone get too close, determined to remain unattached forever.
These exceptional doctors are chosen to work in Paris on a unique project with their counterparts in a mass-casualty training programme. But after an unspeakable act of violence, their temporary life becomes a stark turning point: a time to make hard choices - with consequences that will last a lifetime.