Lu

Lu is one of Chang's sons. He can be found in Lower East Quack, behind a target wall.

How to Rescue
Around the corner from where you rescue Tam, there is an NQPD tank. After the owner has finished talking, shoot the tank and run around a couple of corners, where the target sign is. Wait for the tank to shoot you and move out of the way. Do it to the second sign too, and Lu will be waiting for you on a crate (there is also a Beetle Shield nearby should you have problems escaping the blasts).