In episode 2, where does Ciel acquire the key to the storehouse that the drugs are in?
In episode 2
His butler, Strongest
Several characters are portrayed in the pool room and in the tea room in the scene after.
One of these characters a Chinese male named Lau is responsible for oversight of the drug trafficking that occurs in London.
Ciel being the Earl of Phantomhive, received a mission from the queen to eliminate a rat who had been messing with Lau's business.
Lau gave Ciel the key who baited out his kidnapping and flushed out the rat. Which is why the main focus in the point of this episode was that Ciel likes to play games. He could have had Lau or Sebastian handle it but he would rather throw himself right in the middle a precarious situation for entertainment.