What is the last mission in gta vice vity

The last mission is called "Keep your friends close". you have to try and kill Lance Vance because hes working with Sonny Ferreli the whole time. first you confront him... bla, bla, bla. Sonny orders his to guys to take the money from the safe in your office. then you run after Lance and kill him on the roof. then you have to go back downstairs and get all of your money back. Sonny's men try to kill you but they fail. then your have to try and kill sonny. My best weapon of choice to kill him with is the .357 or a rocket launcher because they're both 1 hit kills.