Burning desire

Burning desire is the 24th mission in Los Santos. As well as the 24th overall.

Mission
Carl enters the donut shop and is spotted by Tenpenny, who tells him to come and sit with them. Tenpenny and Pulaski act with hostility towards Carl, with Tenpenny reminding him that C.R.A.S.H. owns him. Tenpenny then tells Carl that he needs a Vagos Gangster taken out for him.

Carl first heads to an alleyway in Downtown Los Santos to collect some Molotov Cocktails that C.R.A.S.H. had left, before heading over to the building in East Los Santos. Carl kills the Los Santos Vagos gangsters surrounding the building and then throws molotov cocktails into five windows around the building. The Vagos gang member then dies.

Carl then notices a woman trapped inside - to save her, Carl enters the building and gets to the upstairs bedroom she is in. Then, using a fire extinguisher he got, he puts out fires blocking their way, helping the woman escape the building. The woman graciously thanks Carl, and asks him to bring her to her house. Once there, she introduces herself as Denise Robinson, and both of them agree to meet some time later.

Walkthrough
This mission is rather tough. Walking in flames after dealing with many Vagos is no joke, so be sure to have some SMG ammo and optimally, an AR. Body armor as well as health pickups will be scarce around the area, so buy the armor before the mission begins. It's also highly recommended to complete the firefighter side mission, so as to speed it up.

There's a standard LSPD Patrol Car provided by Tenpenny outside. Take it, and go take the Molotovs, then go to the house. If only using molotovs to ignite it, the player should first focus on taking out the guards, which may be hard to see when obstructed by the bushes. Auto-aim will greatly assist here.

After killing the enemies, try to throw the molotovs into the windows. There isn't much skill required, just trial and error. It will be much faster if the player is fireproof, as flames won't be able to damage them.

Once the house is torched, get inside and, depending on your fire resistance or lack thereof, take the fire extinguisher and either sprint straight to the second floor, or slowly take out the flames. There is a time limit, however, so keep it quick and steady.

The house will collapse and block some of the existing routes. While Denise cannot be burned, she will not proceed if flames are in the way. Take them out quickly while proceeding on the alternate route. It should not be very hard, as the structure shows obvious signs to the exit.

Once out of the house, just take a nearby car and drive Denise to her house.

Trivia

 * The building is normally only accessible during this mission.
 * If the Mission fails when the player is inside the building, they will be teleported outside afterwards.
 * The interior of the building shows damage after the end of the mission, although the exterior looks the same.
 * The player will still be forced to collect the molotovs even if they already have enough ones in their inventory.
 * If the player runs out of molotovs before they torch the house, more will respawn near the building. Even if they are all used up, they will still respawn. They will stop spawning once the player has completely ignited the house.
 * For some reason, the molotovs will despawn when the player rescues Denise. This is likely for realism, as Carl cannot allow Denise to realize that he started the fire.
 * Additionally, the infinite-ammo fire extinguisher will also disappear, likely for balancing reasons.
 * There is a wad of $50 in Denise's room that can be picked up, on the table next to her.
 * The Vagos vehicle near the house has it's engine hood open, without any signs of damage, which is otherwise impossible to happen in-game.
 * The gang member calling with a mobile phone is actually holding a pistol instead, despite a fully-detailed model of the phone being present in the game.
 * This mission is one of three to not work correctly if too many cheats are used, the other two being Photo Opportunity and Madd Dogg. At the end of the mission, Denise will not move anywhere near the door of her home during the end cutscene, and will instead roam around the areas shown onscreen and eventually leave the screen completely, making the cutscene endless and the game unplayable without reloading a previous save. Using over 100 cheats before or during the mission will trigger this effect.
 * Molotovs aren't the only weapons able to start the fire. The RPG (which can be found on the roof of a building in LS) is also perfectly capable of doing so with great accuracy.
 * If the player goes outside then back inside after taking out all the flames, the interior will be burning again.