A small school is sponsoring a training conference on nursing education. During the plenary session, a homeless man slips into the auditorium. As he walks towards the stage, he pulls out an automatic rifle and aims it at the lectern. The weapon initially jams, but then a few rounds fire.

The man, bewildered, drops the rifle and runs to an exit. A security guard shoots the homeless man, who dies instantly.

The guard then calls 911. The guard, considered a hero by witnesses and the TV media, is interviewed by the police, who release him, pending a follow-up interview.

The next day, they find the hero has quit his job and vanished.

Then they learn he wasn't a guard - but an international assassin.

The detectives chase the killer with the help of the FBI, two grieving brothers, a nun, and residents of a mental hospital - while also overcoming police corruption.