This page of The Last of Us game guide contains a walkthrough of the High School Escape stage as part of the Bill's Town chapter. This is a demanding level, which assumes, among others, defeating a group of monsters at school (this encounter is enriched in our walkthrough with a map with additional hints), dealing with the bloater mini-boss and escaping from the infected with a pickup truck.
Start of the fight
Suggested player route
Suggested kill areas
Crouch immediately inside the building and slowly make it over to the cover on the left. You now need to clear the room of all the mutants. To do that, you need to wait, at first, until the runner on the left turns away. Then, take him out with your bow.
When the first enemy dies, wait for the clicker on the right. The enemy will turn back at some point, which will make him an easy target for the silent assassin.
After this one dies, grab a brick. You need to use it to divert attention of the clicker stalking a bit further. It is best to throw the object into the classroom and sneak past the zombie to the desk in the corridor.
There is a runner walking around the desk, which you need to kill.
Now you need to get to the other entrance to the room (on the right). Before you take the door, prepare a Molotov's cocktail. You will need it to throw at the enemies who will enter the room right after you do. The ones that do not die, need to be shot, just like the clicker that you outwitted earlier.
This way, you will clear the area and you will be able to open the door a bit further. To do that, you need to press the triangle and then the square several times. At the other side, you will have to fight a bloater and, that is why you need to prepare the Molotov's cocktail beforehand.
The bloater is a formidable enemy which can launch exploding spores. If you are standing within the poisonous substance's range for too long, you will die so, try to move running among the barricades as much as possible.
At the very beginning of the fight, focus on the left corner of this location. After a while, a group of young runners will appear that you should deal with as quickly as possible.
Take cover when they die, and try to hit the bloater with your Molotov's cocktail. If you succeed, the beast will catch on fire and will become defenseless for a short period of time. You can then take several shots at the target and reinforce that with a bomb. This should do for this enemy.
If, the monster survives though, and you do not have enough materials to craft another cocktail, take single shots at the enemy and run to avoid being hit with a spore. You also cannot let the bloater approach you or you will die quickly.
When the beast falls dead, explore the area it came from and then, help your companion climb onto the platform next to the window.
After a moment, two runners will appear behind your back. Kill them and climb onto the platform also.
After you make it out, keep following Bill until you reach a ladder leaning against the fence. You quickly need to deal with an enemy here and jump over to the other side of the fence.
This way, you will reach the garage with a working car in it. Before you give it a push, though (triangle) search through the entire house. There is a lot of useful gear here.
When the car gets out into the road, you will have to keep pushing it and making brief stops for killing the incoming enemies. First, the enemies will be coming from the left, then from the right, and from the left again. First of all, focus on eliminating the clickers because your death is sure if they get too close.
After the car rolls down the hill, you will have to run up to it and, after having driven away the enemies, jump onto the car (triangle).
This way, you will complete this chapter.