In 1863, Confederate soldiers are carrying a gold bullion as a payday for the army. Suddenly, they are cornered and shot by a highwayman using anachronistic automatic pistols and futuristic tech equipment, leaving them stranded and dead. The mysterious highwayman steals the trunk containing the gold and then suddenly vaporizes into a gelatin like mist.
In 1994, 131 years later, the U.S. government creates the Time Enforcement Commission (TEC) to combat the misuse of newly developed time travel technology. They have discovered that the same gold bullion was used in recent arms purchases. The TEC is to detect "time ripples" among the timelines and to stop them from happening before they reach the present, since people cannot travel forward in time to the future, they always travel back to either change history or steal riches.(Note: the mysterious highwayman who killed the Confederate soldiers to steal their gold is never revealed or identified). Senator Aaron McComb (Ron Silver) volunteers to oversee the commission.
Meanwhile, police officer Max Walker (Jean Claude Van Damme) is offered a job as a TEC agent. He meets his wife Melissa (Mia Sara) at a local shopping mall where he stops a purse snatcher. He notices three odd-looking punk men following them despite never seeing them before. Walker and Melissa go home to their large fancy house and later make love.
Later that same evening, Max is attacked in his home by the same intruders he saw earlier at the mall and Melissa is killed in an explosion, destroying his house.
Ten years later in the year 2004, Walker is now a veteran TEC Agent. He is sent back to October 1929, in the midst of the Wall Street crash to arrest his former partner Atwood (Jason Schombing) for taking advantage of the U.S. stock-market crash. After subduing Atwood's bodyguards, Walker interrogates Atwood who reveals that he is working for Senator McComb, who needs money for his presidential campaign. Terrified by McComb's threat to murder his ancestors, thereby wiping out his existence, Atwood tries to kill himself by jumping out a window. Walker catches him as he falls and takes him back to 2004, but Atwood refuses to testify against McComb and the TEC agency sends him back to 1929, right where he left off, this time falling to his death.
Senator McComb arrives at the TEC agency to oversee the work and to congratulate Walker for his recent successful mission. Walker implies to McComb that he knows all about his dirty dealings behind the scenes in Washington and about his means to acquire money for his campaign. McComb leaves the facility and orders his aide to have Walker killed. The next morning, two assassins break into Walker's small apartment and attempt to kill him, but Walker, a trained martial arts expert, kills both assassins after a violent and protracted fight.
While still trying to investigate McComb to expose him of corruption, Walker is partnered with agent Sarah Fielding (Gloria Reuben), and sent back to 1994 to investigate a pending ripple, where they find a young Senator McComb arguing with his business partner Jack Parker about their company's new computer chip. Parker offers to buy McComb's share of the company, but suddenly, the older McComb arrives from 2004 to warn his younger self that the chip will make huge profits. A fight starts when Walker is double-crossed by Fielding, who reveals she works for McComb. McComb kills Parker, wounds Fielding, attempts to kill Walker, and manages to escape back to 2004.
When Walker returns to 2004, he finds that things have become worse. McComb now owns the computer company, with no record of Parker. He is almost guaranteed the Presidency with his finances and approval rating. The TEC is being shut down due to budget cuts. There is also no record of Fielding. Realizing that he has to fix things, Walker hijacks the original prototype time machine (which McComb had been using for their illegal trips) with the help of Commander Matuzak (Bruce McGill), who sacrifices himself when McComb's men try to stop Walker from escaping.
Finding himself once more in 1994, Walker finds Fielding in the hospital, where she agrees to testify against McComb. Whilst trying to find Fielding's DNA from a blood sample in the lab, Walker finds a sample of Melissa's blood and it indicates she is pregnant. Walker realizes her death occurred later that night, and he decides to stop it. After going back to Fielding's room, he discovers that she has been murdered and he is framed as the prime suspect.
He goes to the mall where he and Melissa met that night. Eventually Max finds her and manages to convince her he is from the future. He also sees the three thugs who attacked him and realizes that they are McComb's men whom were sent back to kill him before he joined the TEC.
That evening, McComb's thugs break into Walker's home, like before, only this time the older Walker is waiting for them. Without his younger self realizing it, the older Walker helps to fight off the bad guys. Together, they and Melissa win, though the younger Walker is wounded. The 2004 McComb then takes Melissa hostage. When the older Walker finds the older McComb is holding Melissa, the younger McComb sets a time bomb. He then shoots Melissa, just before the young McComb appears, having been tricked by a fake message from Walker. Walker grabs the young McComb and pushes him into the older one, causing them to become a writhing, screaming mass which melts into nothingness (since according to the time theory, no two persons can exist by physically touching each other).
Walker carries the wounded Melissa out of the house just before the bomb explodes, destroying the house just like before. Walker returns to 2004, and the timeline has been corrected. The TEC still exists, Fielding and Matuzak are alive, and McComb does not exist, having "vanished" ten years earlier. As Walker returns home, he is happily shocked to find himself living in the same house which was rebuilt. Melissa is alive and their 9-year-old son is waiting to greet him. Melissa has something to announce to Walker, implying that she is pregnant again.