Season 4 begins with Mac Taylor (Gary Sinise) returning from a vacation in London and immediately investigating a murder at the Statue of Liberty, where blood is discovered on the statue's crown and face. During the probe, Mac tells Stella (Melina Kanakaredes) that when he was in London he was awakened each night at 3:33 am by an unknown caller who would then hang up. Mac soon learns he is being stalked and the numbers in the phone call's time are connected to his past in Chicago. As for Stella, she begins seeing a new man, Drew Bedford (Kerr Smith), but he's not all he seems to be. And things get more heated for Stella when an arson fire erupts in her apartment building, and it becomes obvious that Adam (A.J. Buckley) has a crush on her. Danny (Carmine Giovinazzo) goes into an emotionally dark place when a 10-year-old boy in his care is killed, and he can't shake the fact that he is responsible for the boy's death. The incident threatens to derail Danny's relationship with Lindsay (Anna Belknap). Meanwhile, Flack (Eddie Cahill) becomes attracted to Det. Jessica Angell (Emmanuelle Vaugier) and the two start dating. The city is terrorized by an unknown taxi driver who murders victims in his cab and then dumps their bodies. Reed Garrett (Kyle Gallner), the son of Mac's late wife, fancies himself to be an ace Internet reporter and begins investigating the case, much to Mac's dismay. Other intriguing cases include: a dying man confesses to a murder 24 hours before it takes place in a case that may involve time travel; a mass murder occurs at the infamous Amityville Horror house on Long Island; Mac becomes an avatar in a computer-generated virtual world to track down a woman's killer; and Mac enters an active crime scene when a bank robbery goes awry and the thief, who is holding hostages, demands that a CSI come in to prove he didn't kill the bank's manager.
