Where is the underground warehouse in Pokemon Crystal?

first, you go to lake of rage in Mahogany Town. then there is a guy that is a guy that is looking at a sign, you talk to him. he will vanish. leave lake of rage. then a sign is next to a house. go in the house. the guy that you talked to at lake of rage is in there. he finds the secret stairs. go down the stairs. that's the underground warehouse. enjoy:) !