Yup! You have to get the quest into Temple of Storms. Then get to the part to defeat Queen Krokopatra. (That cracks me up. XD SHE ISN'T EVEN PRETTY XD.) Then you talk to the guy near the lake and he'll give you the key to MB. BTW, lvl 23 isn't really the lvl or even close to get into MB! It really matters on what you think, but I got in it at 27. Another example is I think someone got into MS at 26. It depends on how you look at it.
I am also trying to go to Marleybone. I have 2 quests now for Marleybone from Harold in the library, but when I follow the quest helper it takes me to the spiral door to the other worlds and the only place I can go is Krakotopia & Grizzleheim. There is no link for me to go to Marleybone...how can I get there??? Please help! Thanks!