Your adventure in LEGO City: Undercover is getting more and more challenging!
The entrance to the mine
Firstly, enter the train. You can use them to get around town quicker. You should simply use the terminal on one of the stations. Go north, to the location indicated on your map.
In order to enter the mine you will have to signal all of the workers, and get them away from the entrance. Go to the small green container and open the safe located inside. Take the valve out of the safe and place it on the pole, to the right side of the workers. Using said valve will unlock the passage to the mine.
The first cave
First, you should disguise yourself as a thief and open the door next to the collapse, then use the lever. Use the blocks that will fall out to build a box, and push it beneath the wall. Now jump up and head to the right. In the small shed you will find a locker with the miner disguise. From now on you can use additional abilities (such as handling TNT) and destroy black boulders by using the pickaxe.
Jump down and destroy the two piles of rocks next to the rubble. Take the yellow switch and mount it on the wall to the right. After using it you will receive blocks, from which you can create a TNT Dispenser.
Carry it to the right, next to the drilling machine, and put the TNT in the barrel. TNT can blow up silver blocks. Once this is done, blocks will fall next to the rubble, from which you can create rails. At the end you should push the cart with the TNT into the rubble.
The second and third cave
In the second cave take care of the three opponents. On the left side you will notice a TNT dispenser. Take one and place it by the silver and blue toilet. Rebuild it and jump into the abyss.
At the bottom you have to build a Cable Car. It is very expensive, and costs a total of 22 000 blocks. If you do not have this many, start destroying objects and collecting blocks. You will find one of the Super Bricks in the red shed.
Destroy the pile of boulders behind the silver cart, and follow the scanner to the hideout which contains TNT. Blow up the cart, build a box, push it and climb up. There, behind a large number of rocks you will find a large Super Brick in the corner, which is worth 10 000 blocks, unlike its smaller counterparts that are only worth 1000.
If you are still short of block for the Super Build, than jump over to the right side. There you will find several smaller and one large block, so you will have no currency shortages. On your way there you will encounter a new element – a fuse. Only a flame from a torch can activate it, you will find one to the right. The torch will lose durability after you grab it, and when the bar fills, the flame will go out. This means that you have to act quickly.
After all of the steps are done, build the Cable Cart and enter it. Your ride will be interrupted, but it will not be much of a problem – jump over to the right and climb up. On the very top you will find an analogical puzzle: destroy the objects in the left corner, build a TNT dispenser and blow up the toilet with it.
You will build a catapult from the blocks, and from the higher position you will be able to jump through the roof and into the shed. There, you will discover a safe – open it. After hearing the message that was inside of the safe and watching a cutscene, you will complete this chapter.