It is time to visit the sewers in LEGO City: Undercover!
Reach the bank
Head to the front of the bank an go into the sewers through the well. First, destroy the green barrel on the left side of the ladder, and go through the barred gate. You will find a valve there. Install it below, in the empty place by the water. Upon using it a hatch will appear, where the key is located. You can use it to open the gate to the next area.
Sewers level 1
Behind the door you will see gas coming from the pipes, preventing you from passing through. Jump over it by going along the railing. You can use the yellow switches to seal the hatches and clear the path. Go to the end, dispose of the two foes and turn the valve. A new device will appear, which can change the colour of paint on your Colour Gun when used. Use it, to gain the green colour.
Return to the vicinity of the gate and use the Colour Gun (hold the attack button as the robber, until a crosshair appears) to hit the red button by the gate. Take the box located inside and carry it to the right side of the room, where you should put it down on the green block and rebuild it. Climb up and go to the second section.
Sewers level 2
In the second section of the sewers you should first destroy the green barrel. There is a scan location underneath it. The tracks will lead to a safe with hidden TNT – put it in the bucket by the wall.
You will build a mattress from the blocks, which you can use to sail through the chemicals located in the water on the right side of the room. Go out when you are on the other shore and defeat the guard. Go to the left and open the gate, behind which you will find a valve. Install it in the opening near the stairs.
After using the valve a stream of water will appear. Use it to get higher up and go to the left. Underneath the barrel you will find some TNT, which you can use to clear the way to the next Colour Swapper to your Colour Gun – now you need the red colour.
Shoot the green ball located behind the boulders, several steps to the right. Go through the open passage on the right and use the ladder to get to the third level.
Sewers level 3
There are several more simple things to get done here: use the Grapple Gun to remove the grate from the wall, destroy the bronze boxes and rebuild them, push the box you will then construct, in order to get through the hole. Take the TNT and use it to blow up the silver objects in the right corner of the room. At the end, open the gate with the crowbar.
Open the safe on the right once in the vault. From the blocks you will be able to construct a Colour Swapper. Shoot with the silver paint at the object in the middle and push it forwards. Now you can move on. You can only move on the right side – the beams of the laser are not very visible, but they are still blocking your way. Pull a similar silver plate towards you. You can now move behind it.
Take the chest you find there to the right corner of the room. You will build another Colour Swapper there, which you can use to paint the wall on the left, so that you can climb up on it.
Use the computer on top and open the uncovered safe. Construct another Colour Swapper. After changing the colour to green paint, shoot the red sphere by the left wall. The bars will open.
Take three valves out from behind them and install them in the walls. Start turning them one by one, until a green light shines above the machine, then click once again to stop turning the valve. Three lamps must be lit, in order for you to gain access to the gem. Take it and escape through the passage that was opened by the guards, who entered the vault.
You will now head to the top part of the bank. After eliminating three guards, you will have to collect 30 000 blocks, in order to build a getaway vehicle. On the left wall you will see three machines with numbers on them. Set the numbers X, III, VII, by turning the knobs. A key will fall out, which you can use to open the door, that will get you behind the reception. Inside you will find a large Super Brick and some TNT.
Go out with the TNT and place it by the statue in the right corner of the hall. This way, you will gain entrance to the second reception. There, you will be able to find two more safes will Super Bricks in them. When you are ready, start the Super Build. Flee with the vehicle to the designated location. You can safely crash into and run over enemies.