Underground Laboratory/R&D Access
Before you jump into the well, run around it and take a Blue Orb Fragment. Jump down and enter the door. Dangerous fish - Cutlass, will attack you. Destroy those using Charge Shot.
In this room you need to play a board game. The goal is simple - you must reach the end of the board. Attack the dice with a sword to throw it. Each color has a different effect: red - enemies appear; blue - prize; white - no effect; yellow - free move.
Angus is not you main enemy in this room. You just have to destroy a forced glass using Gladiuses (flying swords summoned by Angus). Snatch them, then throw it with a Buster. Repeat this. Be careful of the high voltage floor - jump over the platform to avoid it.
Attack the blue glowing machine. Go upstairs, but before you leave through the door look at the edge of the platform. You should notice a Blue Orb Fragment floating in the air. You can take it using Snatch 3 and Air Hike/Roulette Spin.
There are some Bianco Angelos to destroy and secret mission 04 (on the left side of the body in the cage).
Secret Mission 04: Tracking Treasure Down
Find all hidden Red Orbs.
Tactics: Nero's hand glows when he is near hidden Orbs.
Underground Laboratory/Grand Hall
Near exit, activate the panel and get out of the shaft jumping on the red platforms. Go along the corridor and leave the lab. When you reach Grand Hall pick one of the doors near the picture.
C. Courtyard/F. Falls/F. Entrance
Destroy Frosts and finish this mission walking over the bridge.