Count Di Savoia was a dinner guest at Mrs. Lancelot Van Meter's party, where he stole the Hope diamond from her. Scoop Cody is put on the case with a police captain. The captain deputizes Cody for the case.
Looking at the dinner list, Cody and the captain decide to interrogate Di Savoia. Knocking on the door of the count's hotel room, they are admitted after the thief hides the diamond by securing it beneath a table with chewing gum.
Frustrated in their search, the captain and reporter leave to return to police headquarters. The count meets with his henchmen, informing them that he can't show them the diamond as it's too hot.
At headquarters, the captain and Scoop check the files. Scoop finds that Count Di Savoia has an arrest record as an international jewel thief. Scoop notes that the files say the count is known to always be chewing gum, yet he was not when they saw him at the hotel.
Two of the count's mobsters go to the hotel to demand to see the stone. After a battle, the count gets the drop on them with a gun and sends them packing. After the gunsels leave, the count calls his girlfriend Gertie to inform her of the ocean voyage the two of them are going on. After hanging up, she is accosted by the toughs Count Di Savoia just defeated who demand to see the stone.
Meanwhile, the count finds Scoop Cody with the stone after the reporter searched the hotel room. The two battle, but Gertie shows up after escaping while the mobsters searched her room. She gets the drop on Scoop with a gun. The pair of paramours incapacitate Scoop by tying him up before leaving for the ship. Count Di Savoia's thugs show up on the pier as the ship and see the count and his girlfriend board the ship.
The Marvel shows up to the hotel and unties Scoop. Two of the gangsters hold Count Di Savoia and Gertie at gunpoint, demanding the gem. The count refuses, and as they search their luggage, Di Savoia surreptitiously places the diamond in a wad of chewing gum and sticks it to Gertie's back where it is left nude by the cut of her dress. One of the gangsters start choking Gertie, demanding to know where the stone is.
Scoop and the captain show up and rush the remainder of Count Di Savoia's gang, but are soon overwhelmed. Luckily, The Marvel gets the drop on the gang from a porthole in the ship. The police arrest the gang, with Scoop explaining that he watched Count Di Savoia place the gem in the gum on Gertie's back. Scoop's boss commends the reporter for a job well done.