Now it's dark. Use the night-vision goggles and the targeting of the OICW if you're having trouble seeing. Make your way back up the ladder to the main stairway. Get ready to fight more elite guards, who will be descending on you.

Make your way back to the cave complex.

Get to the stairs and climb up. Fight your way back to the lab areas. Most of the doors have been sealed with the power outage, but you'll see some scientists breaking a window with a chair. Once the window is out, jump though and find the open hatch. Drop down and crawl through the duct.

Fight the guards in the next room, then go through the double doors. In the next lab, wait for security windows to open, then kill the visible soldiers. Go through the door and then take an immediate right. This will take you back to the cave complex.

Kamchatka: Cave Complex
Objective: Gain entrance to the research facility

Pick the lock on the door, then follow the hallways to a ladder. Climb up, and fight your way through the white brick corridor.

You'll find a locked door here that leads to the research facility. You can't open it yet. Back up and find the nearby elevator. Flip the switch to open the roof hatch, then climb the ladder to the top of the elevator. Climb the elevator cables to the very top. Make sure you have a safe place to land, then drop off the cable.

Open the hatch and climb up the elevator cables.

Either grab the M60 or get to the double doors. Make your way back down the stairs and into the main floor of the cavern. Note that some previously sealed doors in the computer room are now slightly ajar, and you can find some supplies behind them.

Once you are on the ground floor of the cavern, turn right and head over to the conveyor controls. Flip the switch to drop the cargo into the ravine below. Now go all the way back up to the elevator and climb down the cable.

Return to the locked door you encountered before climbing the elevator shaft. You'll need to jump a large gap, but the door will be gone. Proceed to the research facility.

Kamchatka: Research Facility
Objective: Get to the labs

At the bottom of the steps is a locked door. Pick the lock for some supplies. Follow the hallway until you come to an intersection. Head left. Follow the hallways until you come to a scientist trying to open a door. Pick the lock, head through, and go up the stairs.

Turn this valve to flood the room and open the locked doors.

Fight your way to the end of the hall. It appears to be a dead end. Throw a grenade to shatter the windows, then drop down into the room below.

Jump through the open window of the central room. Turn the valve to flood the room, which will in turn open the doors just outside. Head through the doors, jump over the debris, and prepare for a big fight in the room beyond. Once the path is safe, move forward into the main labs.

Kamchatka: Labs 1, 2, 3

The power is back on. Go through the door into the first lab. Try to set a charge on the shiny, expensive-looking thing. Head out and to the left.

You must move both cargo pallets to find the explosive charges.

You'll find a door to a small area with trucks and military supplies. On the platform in the center is a switch that controls the cargo. Flip it twice to bring both pallets to the platform. The second has some charges on it. Return to the lab and set the first charge.

When it explodes, it will leave a huge hole in the wall behind it. Go through it and into lab two. Be very careful of the hallway just before the lab--it is a significant choke point.

The duct across the way is your doorway to lab three.

Climb down to lab two. Set the charge and take cover. After it explodes, a small wave of soldiers will appear on the walkway above. Get back up to the hallway, and look through the now-destroyed windows. You'll see a closed duct on the opposite wall. Shoot it open, then make your way along the ledge toward it. Crawl through the duct and into the hallway. Shoot the next duct and crawl through it.

When you get to lab three, jump over the console and flip the switch to open the access door. Go in and set the charge. After the third lab is destroyed, some soldiers will open the door to lab four. Kill them and proceed.

Kamchatka: Lab 4

In the final lab, you must first unlock two security doors leading in. Once you can see the lab equipment, head down and flip the two switches on either side. Then head into the main control room and flip the switch to raise the cover.

Bio Lab Four is no more.

Set the charge, then take cover. Once the final lab is destroyed, head up the stairs. The shield that previously covered the equipment will be going haywire, raising and lowering. Jump on it, and ride it to the ceiling near the vents above. Crawl along next to the vents until you hear someone yelling at Dr. Sestrogon. When you reach the end of the area, you'll fall through into the room below.

Shoot the guards from the cage to escape.

Kill the guards and talk to the doctor. Follow him out of the lab.

Go down the steps and pick the lock on the door below. Flip the switch to call the metal cage. Get into the cage, and flip the switch when you are ready. Once you're in the tunnel, shoot the guards below, then turn toward the door of the cage. Shoot the guards ahead, then wait until the cage stops. Exit and watch your debriefing.