Going Undercover is a mission in LEGO City Undercover: The Chase Begins. The Robber disguise is unlocked in this mission.
Walkthrough[]
Upon arriving at the prison, Chase immediately realizes that he is going to need a better disguise to survive here. So follow the studs inside the prison proper where you can find a costume closet. The problem is the way to the actual closet is blocked off.
First, smash everything. Throw the lever together and then pull it down to make more stuff fall from the ceiling. Build the stuff to create a small trampoline. Then use your magnifying glass to find a valve buried under some dirt. Use the valve on the pipe to close the shutters on top of the furnace.
Now, go back to the trampoline and hold the B button to build up some height. Jump across to the ventilation shaft hanging from the ceiling and work your way to the ledge. Shimmy across and then drop down onto the furnace. Jump over the fence and then open the closet to get the Robber costume. Using this costume, just like in the Wii U version of the game, you are able to break through doors with a Crowbar.
Using a Crowbar, break through the initial door by mashing on the A button. Then go back outside. Use your crowbar to break through another area and then you'll come up to a bunch of grey boxes. Push the initial grey box up to the stack of other ones so you can get over the fence and then watch the next cut-scene.[1]