John Q. Archibald (DENZEL WASHINGTON), his wife Denise (KIMBERLY ELISE) and their young son Mike (DANIEL E. SMITH) lead a relatively happy life despite their various financial problems that stem from John's hours being cut back at the factory where he works with his friend, Jimmy (DAVID THORNTON).
When Mike is suddenly stricken ill and Dr. Turner (JAMES WOODS), the head cardiologist at Hope Memorial Hospital, informs the Archibalds that their boy needs a heart transplant or he'll die, their world is shattered. It gets worse, however, when hospital administrator Rebecca Payne (ANNE HECHE) informs them that John's health insurance doesn't cover that operation and its related costs, and that unless they can come up with a $75,000 down payment on the total $250,000 amount, Mike won't be put on the transplant waiting list.
To his shock, John learns that's true, and so the two set out to raise the money any way they can, including sell most of their personal effects. When that doesn't raise enough and the hospital announces it's going to discharge Mike, John becomes desperate and takes Turner and a handful of other people in the emergency room hostage.
Among those held by John is Mitch (SHAWN HATOSY), a cocky young man with a penchant for beating his lover; Lester (EDDIE GRIFFIN) a wise-cracking man who there's with a bloody hand; expectant parents Miriam (TROY BEYER) and Steve Smith (TROY WINBUSH), and Max (ETHAN SUPLEE), the unarmed security guard who isn't about to risk his life for such a low-paying job.
Arriving on the scene is veteran hostage negotiator Lt. Frank Grimes (ROBERT DUVALL) who tries to go through the normal drill, but must deal with Monroe (RAY LIOTTA), the police chief who shows up and wants his men to take out John as quickly and quietly as possible. Unfortunately for both of them, smarmy TV reporter Tuck Lampley (PAUL JOHANSSON) also shows up, as does a horde of supporters who crowd the streets and cheer on John's efforts.
As Mike gets sicker and the police get more edgy, John must deal with the various issues that pop up in the ER, as well as the increasingly intense hostage situation, all as he attempts to force the hospital to put Mike on the transplant waiting list and then finds himself forced to take extreme measures to make that happen.