Riddles in the Dark Ep 15 - Shinar's Heist

Shinar smiled to himself as the guards searched his pockets. He heard the crowd of the party outside, all rich lords and ladies, murmoring and muttering. 

"I assure you I do have nothing that do not belong to me" he said.

"Shut up thief! We know you have the painting somewhere!" The guardsman said. But they never found it and were forced to let him go. 

The mystery: How did Shinar get the painting out of the room he was in, and what was his plan to sell the stolen artwork?