Free the Treasure

Head to the new city district after destroying the second Omega Guardian. Talk to Katt Burglar beside a police car to accept this quest. Head south and enter the Bank of the Naughty Boy hideout.

Once inside, clear the furniture and goons in the first and second rooms, then go through a trap-laden corridor until you reach the room with the first goons' loot.

Head to the next room to the NE and clear the enemies there as well. Go forth and cross another room with fire traps, and the next one with a rotating laser. The room with the rotating laser has three possible paths, each has traps and more enemies.

The doorway leading to the NE leads to two dead-end rooms with another goon's booty and “City” character chest.

Again, from the central room with the three doorways, head to the SE and follow the path with similar traps and you'll find the last chest with the goon's booty.

Finally, backtrack to the middle room connecting the branching paths then go SW this time. Pass through the trapped corridor and clear the following room to reach the hideout's computer. Talk to Katt Burglar to complete the quest.