Before this mission is available, Bernie will contact you, telling Niko he needs his help and fast. Bernie explains to Niko about coming to Liberty City to be himself and is now being threatened by a homophobic man everytime he goes to the park to exercise. Niko agrees to help Bernie and they both leave for Middle Park.
You can either walk or take the Comet at the end of the road there. When you arrive at Middle Park, Bernie warns you to stay back while he runs to lure the enemy out but don't wonder too far. Bernie runs underneath an overpass which triggers another scene. As Bernie is running underneath, the homophobic man is wielding a bat and comes out, attacking Bernie. Niko comes into the scene to defend Bernie and the scene ends with the man running up the stairs next to him. You must now chase him and get onto a scooter at the top. Equip yourself with a machine gun or pistol and start shooting. The enemy will continue driving around the park until he is eliminated.
Once he is dead, you must go back to pick up Bernie, who wants you to drop him out at Perseus in The Exchange to go shopping.