Former U.S. Army Special Forces sergeant Chris Vaughn (The Rock) returns to his small home town in Kitsap County, Washington. Looking for work, he finds the local cedar mill was closed down three years prior by its heir, Jay Hamilton (Neal McDonough), who opened a new casino that now accounts for the majority of revenue for the local area. Hamilton, who was also Vaughn's school friend, invites him to a night of fun at the casino. While checking out the VIP lounge, Vaughn stumbles upon his childhood friend Deni (Ashley Scott), who is now working as a stripper. Later, he notices the craps dealer using loaded dice and demonstrates this to the patrons by placing a bet and calling out the roll before throwing the dice. When the floorman declares no payout, Vaughn instigates a fight. Although he beats down most of the security guards, he is subsequently subdued with a cattle prod and knocked unconscious. The security staff take Vaughn into the basement and Hamilton's right-hand man and head of security Booth (Kevin Durand) tortures him by cutting his torso with a utility knife before dumping him on a roadside. He is found by a trucker and hospitalized, but recovers quickly.
Vaughn goes to the sheriff, Stan Watkins (Michael Bowen), to press charges against the guards, but Sheriff Watkins refuses to allow him to do so because the casino is viewed as too important to the town's economy, stating that because of its position, the casino is considered a "no fly zone". After this, Vaughn also learns that his nephew, Pete (Khleo Thomas), experimented with crystal meth, which was sold to his friends by the casino security guards. Infuriated, Vaughn goes to the casino, and using a piece of lumber as a club, begins destroying casino property, and brutally beats the security guards when they attempt to stop him. Vaughn is apprehended by Sheriff Watkins and his deputies as he is driving away from the scene.
In the ensuing trial, all of Hamilton's security and staff testify against Vaughn. When the judge allows Vaughn to present his defense, he fires his appointed attorney, who is implicitly under Hamilton's employ. After making a civic speech about the town's great former self, Vaughn tells the jury and the rest of the town that if he's cleared of the charges, he will run for sheriff and clean up the town. To further emphasize his plea, Vaughn reveals the grotesque scars on his torso from his being tortured by the casino staff. He is then acquitted and wins the election for sheriff. Upon taking office, he summarily dismisses the entire police force and deputizes his friend, Ray Templeton (Johnny Knoxville), whom Vaughn feels he can trust, as well as help Vaughn learn about narcotics (Templeton revealed earlier that he served time in prison after becoming a drug addict).
Vaughn and Templeton find drugs on Booth and they take him into custody. In an attempt to make him reveal information on the town drug operation, they hold him captive in a garage and proceed to strip his truck into pieces in front of him, but he does not talk. Vaughn assigns Templeton to stand watch over his house, as he knows Hamilton will likely target his family. Vaughn himself remains at the sheriff's office to supervise Booth. He is visited by Deni, stopping by under the pretense of bringing him food and reveals that she quit her job as the casino stripper. The two end up spending the night together in the office. The next morning, Watkins and his deputies arrive at the Sheriff's office where they blow up Vaughn's truck and fire upon the building with machine guns. Recognizing his dangerous predicament, Booth pleads for Vaughn to let him out of his cell, prompting Vaughn to use Booth's perilous situation as leverage for information. Booth reveals that the old mill is where the drugs are being produced, but is immediately killed by the indiscriminate fire of the attackers. Vaughn manages to kill all of the attackers with Deni's help.
Vaughn's parents' house is attacked, but Templeton and Vaughn's father are able to dispatch the gunmen. After ensuring their safety, Vaughn heads for the mill where he discovers a meth lab as well as Hamilton, calmly waiting in a control room. Hamilton attempts to kill Vaughn with the mill equipment by dropping him through a trap door, but Vaughn drags Hamilton down with him and the two fall through a chute. Vaughn, whose leg is injured, manages to tend to his injury in a nearby forest before Hamilton attacks him with an axe. The two fight for their lives, with Vaughn ultimately coming out on top by beating Hamilton with a nearby uprooted tree, breaking his leg. Vaughn repeats what Hamilton said to him earlier "You're right, Jay. This does change our relationship. This is my town. You're under arrest." And Hamilton is arrested and taken into custody, with Templeton's assistance, Vaughn shuts down the casino. In the closing scene it is revealed that the local mill is back in use.

Question: Why did vaughn go to casino and destroyed the property?
Answer: he destroyed the property because he found out that his nephew had experimented crystal meth supplied by guards
Alternative answer: He wants to clean up the town