Chain of Evidence - Sleeping Dogs
After completing the last mission, you'll receive this from Tifany. Head to Club Bam Bam for a scene. After that, call Raymond. Meet him next in the North Point Underpass. You'll then have to recreate the scene. Consider this as your firearms training in the game as well. Just follow Pendrew's instructions, especially the vault shoot mode which you can definitely use later on. After the mission, lose the cops to receive the next mission.