You will need the police dog. First, have Jake go up to where the warehouse is located. Jump on the first platform, then on a crate and push the button. Then, get the German Shepherd and have him climb up on the roof and take the jumps. Once inside, have him grab the big "blocks" and pull them out in a line, then down. The opening across from the entrance has a bone. To save time you can have the German Shepherd get it and toss it down. The middle one leads to the bandit, and the other one is a dead end. Once in the middle one (with the German Shepherd), run down the ledge/path. Once in the warehouse, walk slowly (no barking) down the ramp and around the path and down again. Have the German Shepherd pull the lock on the door, then run back up underneath the bandit. The "Pick Up" option should be available. Have him grab the mask, and he will automatically take it back to the cop.