Where do I find the plunger!?

well it all starts out in lighthouse fright house part 2, get 500 scooby snacks to unlock the snack gate and go in. Theres also a shortcut instead of the lighthouse way, get to the end of smugglers cove where the creepy groundskeeper is and do a supersmash on the wood in the clearing, fall into the hole.Then u will see a yellow ghost, behind it theres a yellow fish monster, kill it and smash all 3 square buttons, it will unlock a gate, go through it, dodge all of the rocks, and go through the next door. u r now in part 2. u will see a gargoyle, [b]KILL IT! Walk to the LEFT and collect all 4 keys from over the witches pots. Retrace your steps to the RIGHT until you come upon a small door, go through it. Kill both zombies then come back to the entrance of the tunnel. walk into the second door on your left. enter the door on the left side of the room.ur now in part 3. go up the stairs and dodge all axes, make sure your health is high. go up one more flight of stairs and enter a room FULL of ghosts. activate the warp gate and make your way to the back of the room. in the clearing in the back of the room you will find the plunger.

When you find shaggy in part two how do you get the key without having the umbrella? I am confused, so to get the umbrella you need the plunger, but to get the plunger it seems like you need the umbrella. So how do you get the key to get shaggy out of the cell, so you can move on to get the plunger? Please EXPLAIN to me how to get that key because I am stuck.