Finding the lion
Go to Emerald Ranch. The escaped lion is supposed to be here. Go to the barn – two men are holding the door. Go inside the building and move to its back. The lion escapes from the barn.
Go outside and examine the farmer’s corpse. Arthur determines that he is about to face a real lion. The short investigation (you can follow the blood trails) takes you to the stable presented in the picture above.
Enter the stable – the game will play a short cut-scene. Kill the lion before it gets Arthur. Use the Dead Eye to shoot a few bullets at the animal’s head. You can get a trophy from the lion.
Go back to the circus caravan and speak with Margaret. You receive an Emerald – you can sell it to, i.e. a fencer for $50.