When you step off the tower after the dark plants, it goes up. You're told there are four power junctions to take out. Walk out the doors, and you'll find a vehicle is waiting for you. Fly along to the green spots on the map. In general your task is to stop near each one and shoot the enemies. Note that your pal has a health bar, so you have to keep him alive.
The key here is to get to each target as quickly as possible. You then immediately get on the ground so your pal can jump out quickly before the bad guys show up. Then fire like crazy to protect him while he does his job.
When you get all four of them, you're abandoned - but you get a Needle Lazer. The needles home in on targets, but are short range and can't turn well. Now you hear word of a shipment that is worth stealing. Your task is to find a vehicle with Eco and drive it back out. Note if you haven't been doing your ammo secrets it is time to go enable them all! They really help you conserve your ammo well.
Note that as soon as you hop on the shipment vehicle, rockets are IMMEDIATELY chasing you. You have to drive straight and fast. First you have to get out of the maze area without hitting anything. This comes down to practicing and knowing the route. Once you get out of the maze, you checkpoint there.
Now you're in the open area. Go low and shoot the blue bubbles - each one will distract one missile. Go high to get over the bridges. You have a timer here to encourage you along. The last missile is done as a cut scene with the ocelot statue being blasted.
You've got two choices here - to go into the bar (martini symbol) or back to the desert (blue hamburger representing the shuttle).
Go back to the bar - there's word of a new assault. This is an arcade-like run-and-gun mission, with your task of saving people. You simply clear enemies off of each screen. Note if you grab a weapon you see, you're now stuck with it. There are no weapon choices other than walking over one on the screen. The game 'moves' you from scene to scene automatically as you kill the enemies.
Finally you are done and end up in front of the weapons shop. Go in the little door. The girl says she is in love with the ocelot. She also has a new course for you. Your goal is 11,000; Bronze is 13,000. When you finish you get a Plasmite RPG and new secrets.
Jak and Daxter 3 Walkthrough