Mystery at Mikey's Mansion - 'Welcome Home' (2)

“Look at what he has done to my elegant homestead!” Mikey announced as he walked about the foyer. “This area is a mess, that pillar has a lockbox on it too. I’m going to see what else is new.”

Daniel too noticed that there was a lock box on the left frontmost pillar. He also noted that the door at the back of the room had four cards on it. “You do that, I have to check something out.” Dan replied.

Dan looked at the door, there were metal panels behind the cards, he tried to move them, but they wouldn’t budge, not even a millimetre. The four cards were a Queen of spades at the top, a King of hearts on the right, an Ace of clubs below the queen of spades and layered atop the card’s midsection, and the card on the left was a jack of diamonds. The outlines of their suits were visible but inside were buttons. Daniel knew what he had to do. He put in the three stones he found earlier. But he was still missing the last stone. Where was it?