The Dead Pool

For San Francisco veteran police detective 'Dirty' Harry Callahan (Clint Eastwood), fame catches up with him when he testifies against crime kingpin Lou Janero (Anthony Charnota) which puts Janero into prison. One night, Callahan is attacked by Janero's men at a turnoff near the San Francisco Oakland Bay Bridge while driving his car. However, he knocks down one of the assasins with his car and shoots the remaining men dead before they finish their jobs. Afterwards, Dirty Harry Callahan and his new Asian-American, martial arts-skilled partner Al Quan (Evan C. Kim) are assigned to investigate the death of rock singer Johnny Squares (Jim Carrey).After slasher film director Peter Swan's (Liam Neeson) producer is killed in a Chinatown restaurant robbery which Callahan foils, Callahan discovers that he, together with Johnny Squares are part of a game in which participants try to predict the most celebrity deaths, presumably from natural causes or from those that work in dangerous professions, and in a turn of events, two more celebrities on the list are killed.Along the way Harry has to deal with the media, particularly reporter Samantha Walker (Patricia Clarkson), to balance their interference with the investigation against the public's right to know. She also proposes to do an in-depth profile on Callahan for her news report, while he wants to simply perform his job and stay out of the limelight. After one dinner meeting, they narrowly escape being killed by Janero's men in an elevator outside a restaurant, leading the reporter to reconsider the plight of police officers.The following morning, Callahan drives to the prison where Janero is serving his sentence to meet with a chain smoking inmate named Butcher Hicks (who is very large and muscular). Callahan promises Hicks a carton of Camel Un-Filtered cigarettes if he helps Callahan out. When Callahan reaches Janero's cell, he makes it clear to Janero that if something happens to him, then Butcher will pay him a visit and probably kill him (this results in Janero telling his men to make sure nothing happens to Callahan while he is on duty).Callahan helps resolve a situation where a man named Gus Wheeler (Louis Giambalvo), who is rumored to be responsible for the murders, tries to burn himself to get on the news so people will know the real him. In the end, it turns out that the real killer is a deranged fan of Swan, named Harlan Rook (David Hunt) who thinks all of his ideas and work have been stolen by Swan. It is also known that Swan had filed a restraining order against Rook a year before.Next morning, Callahan and Quan are pursued through San Francisco's hilly streets in an unmarked squad car by a remote controlled bomb assembled by Rook, disguised as a radio controlled car. The bomb explodes, nearly killing Quan who survives due to his bulletproof vest. Meanwhile, Rook, disguised as Swan, calls Walker at the television station to Swan's film studio to give her an interview, which is actually a trap. Soon after, Rook's home is raided by the police and torn posters of Swan's films are found.Callahan then drives to Swan's film studio where Walker is held captive by Rook. Callahan reluctantly surrenders his .44 Magnum revolver to Rook when he nearly slits her throat. Walker and Callahan escape and Callahan lures him to a pier after a chase. Rook, who has run out of bullets, is shot by Callahan with a harpoon, killing him instantly.As the film ends, Walker and Callahan are leaving the pier, while the police are arriving at the scene.

Question: Who does Dirty Harry testify against?
Answer: Lou Janero