You know there has to be a mistake when Leo Gorcey inherits a spooky Long Island mansion. Spooky mansions only mean one thing in movies, that there is villainy afoot. Otherwise why would you have trap doors, hidden rooms and the like built into your home.
The place is actually owned by another Terrence Aloysius Mahoney if you think the world is ready for another one. This one is played by Paul Harvey who has a command of the English language, but is a rather tired and put upon individual who also visits his Long Island home where caretaker Eddie Gribbon has allowed a group of smugglers headed by Martin Kosleck to operate.
Harvey and the Bowery Boys come separately on the same night, Harvey to visit his house and Gorcey and the gang to claim it. After that it's the usual group of gags that occur in every haunted house picture.
Smuggler's Cove is a pretty good Bowery Boys film, but I personally prefer Hold That Ghost where Abbott&Costello did so much more with the haunted house genre.