You start after Murray drives the van over the Great Wall, and parks at the end. When you start, walk to the left of the gate, collect the clues in the area, then hit the two guards there. As you continue up the hill, a Gorilla Defender, one of the Panda King's guards, attack by catapulting smaller monkeys towards you as they roll and get covered in snow. Dodge them and get away or attack.
After exiting the cave-ish area, watch a large rocket hit a mountain, causing an avalanche to bury a nearby village. Continue on by swinging up to the higher ledge, heading into another cave-ish path. Dodge another wave from a gorilla defender, then attack and walk over the wood bridge. There will be a large gap halfway in, so use the hook to leap. Next, you need to shimmy past two ledges with falling icicles. The second ledge has more of them, so watch out! When you get off the ledges, dodge the snowballs from the welcoming committee of two more gorilla defenders.
Several blue rockets are at the back, and they provide a coin or two, and a light show when hit. A red firework is next to them, so hit it to hit the hinge on a door to make it fall. Bounce, then use the tactic you used to hide behind walls to dodge the Ape General below and hit him. When you sneak around the building, make sure the light is on your far side before you go under the awning. Climb the ramp and hit the fireworks to kill the three guards on patrol. Collect the clues near the windows and head over to the far side of the roof where two more fireworks are set up. Hit them to knock down the drawbridge leading to the vault and door, and destroy the hatch in the room. Cross the drawbridge and knock out the mandrill guard to the right. Then crack the safe for a couple more clues.
Here comes the hardest part. About eight ape generals are on patrol around the path to the key, so you have two options; mine each of them, or sneak past them. If you want the vault page, use the mine to eliminate the task of dodging lights while getting the clues off the wall. When you are done, open the key case and before unlocking the door, head to the vault and dial in 5-7-8 to claim your reward. Then head up to the gate to unlock it and enter the main hub level, "Inside the Stronghold."