Gears of War Act 2 - Tick Tick Boom
After the cut scene Marcus will have control of the squad. Follow path to right turn.
Anya will notify Marcus that Hammer of Dawn is offline. At corner turn right head straight ahead. You'll be given a choice of left or right path. If you choose the left path, you will get blocked by a door. Choose the right path option.
Follow the path and climb the ramp. At the top of ramp jump the rock. Climb the stairs to the top. A cut scene will play. After the scene there will be two big Locust in a hole in the floor. Kill them to open the door blocking the other 2 squad mates.
Go around the hole in the floor and exit room on the left path. Head down the hallway to the left. A Locust will attack. Kill him then jump the rock. There will be an opening to the left.
Enter the opening and exit this room through the left opening.
Go through the door to the left and around the platform to the stairs. Go down the stairs and follow the corridor to the car. Locust will attack both parts of the squad.
Go around the car and to the left to find a door in to a building where Locust will be fighting the other half of squad.
After the Locust are dead the squad will regroup up. Go up to door and kick it open. It won't open. Marcus will ask for some help. Jack will decloak and rip it open.
Follow the platform around the left to some stairs. Climb down the stairs and jump the rock. Kick open the door.