You can beat the Mission and keep your friends close on GTA Vice City. This is really hard one and it may take time. Follow the simple steps below

Stock up one all the weapons you can get from the ammunition store and where ever you can find weapons.

Get the SMG machine gun, and sniper rifle and just get all the bullets for those two guns.

Save it before you go to the mission that way if you die you can just reload the game and still have all of your ammo and armor without having to buy it all over again.

As soon has you start the mission hide behind the desk and pick off any of sonny’s men that come from the stairs.

Pretty soon after killing about 20 of sonny’s goons Lance the Backstabber will say “no one to cover your @ss now Tommy”. You should run after him shooting at him and any guards that get in your way

He will run to the roof of the estate. Just get the slow motion thing to the left of you as soon as you get on the roof.

Kill the guards first then try and kill Lance. He takes a lot of hits but he will finally fall making that the last dance for Lance Vance.

Run back inside your mansion and use the sniper rifle to kill Sonny from the very bottom of the room.

Note

If you start taking too much damage just run to the basement there should be health, armor, a shotgun and a M16 there for you uses

Also you can kill Lance before he gets to the roof by getting a m4 and going the alternate route instead, and even before Tommy says “come back here backstabber” by using the spaz shotgun (if you’re quick enough)