Reach the Plant Nursery
Flash the closed plant beside the entrance gate for its key, then enter the Courtyard and inspect the Hydro Generator. Take the key from the chest on the right. Back outside, vacuum the leaf covering the left door and enter the Tower Lobby. Reveal the hidden Greenhouse door with Dark-Light and cross the falling-obstacle route. Flash shovel-carrying Greenies only when they uncover their faces, then exit onto the opposite side of the Tower Lobby. Search beneath the stairs for the first emerald before climbing to the Plant Nursery.
Cross the Skybridge and float through the Laboratories
Vacuum a spiky fruit from the nursery table and shoot it into each Flytrap. Take the chest’s key. Cross the upper Tower Lobby carefully: the rug is a trapdoor that sends you back down. Run across the Skybridge between the birds’ passes and unlock the Laboratories. Clear the Slammers and Greenies. Grab the purple Bulb, stop vacuuming before swallowing it, then blow air to inflate it. Float past the spikes to the upper landing. For the second emerald, use the middle-height wooden ledge to drop into the glass tube before returning upward.
Restart the rooftop pump
Enter the Water Supply and climb to the Rooftop Pool. Catch the ghost holding the bucket, fill the bucket under the water flow and place it on one yellow floor panel. Stand on the other panel so all four green switches are exposed. Charge the Strobulb and flash all four together; individual flashes will not start the pump. Capture the ghost that interrupts E. Gadd’s call to finish. For the Boo, restore the missing drawer cabinet at the back-right of the Hydro Generator and vacuum its Spirit Balls.
Collectible checklist
Haunted Towers gems — #1 Tower Lobby, #2 Laboratories
Boo checklist — Hydro Generator: Restore the drawer cabinet in the back-right corner and inspect it.