Ann will be kidnapped again, but also saved thanks to the Kong's actions.
In the beginning jump and catch the crane. Then get to the gate (it'll be destroyed).
You'll enter the natives' town. Go down the stairs and kill every encountered opponent. Then move to the next gate.
Go through it and climb the vertical wall. From there, jump towards the sticking out element, and then on the platform (picture).
Get rid of natives there and again catch the stone element to move near the next gate.
It'll be buried with pillar. Some enemies will try to stop you, so eliminate them. Throw the pillar away. Move towards the screen, in the direction of stone's elevation. Destroy the wooden construction (now, there're two ways - I'll describe the first, the other is showed on the map).
Approach the gate and jump right (picture on the right). There will be two handles. Use them to get on the tree...
...from there jump on stone shelf, where are some enemies. Now come back to the gate and go trough it.
You'll go down the stairs, killing all showing up opponents.
You'll find place filled with lava behind next gate (run as fast as you can, because lava's level is increasing constantly). Jump towards the screen to get to Ann. Pick her up and move ahead.
You will reach the destroyed pillar with the tree at the top. Climb up and leave Ann on the catwalk, because she'll help in setting the bushes on fire. Wait for you love, pick her up again and jump to the nearby wall.
Climb up and then... jump down on the other side, to the lake. Now, there won't be any obstacles on the way. Move towards the beach.
Carl with the others will attack Kong with sleeping gas there. Unfortunately, it'll be strong enough to strike down the gorilla.