The player is a rookie police officer named Jake Ryan. Jake's father was a police officer, which prompted Jake to join the force. Jake's father was killed in the line of duty and his case has not yet been solved. While playing the game, Jake uncovers clues to his father's murder.
Jake graduates at the top of his class and joins the Jackson Beach PD, the same force his dad was on. He makes several arrests in connection with a National Guard armory break-in. Just as he is about to tie these crimes in with his father's murder, Jake is in a car accident while riding his police motorcycle. After spending weeks in rehab, his father's old partner offers him a job as his assistant in his private investigation firm, and Jake accepts. Eventually, the two discover a massive gun smuggling ring, tied to three main individuals: a man named Bradford Green, Stuart Cox, the Jackson Beach district attorney, and Nico, the person who murdered Jake's father. The game ends with Nico being sentenced to receive a lethal injection, Bradford Green being sentenced to 20 years in prison, and Stuart Cox being sentenced to 15 years in prison.
Source: Wikipedia, "Blue Force", available under the CC-BY-SA License.