Thief, background for flavor to get some good RP in. By the time you are 9th level you will have the skill and tools needed to call yourself an expert.
What do you see needing to escape from. Both Athletics and Acrobatics will come in handy for stunt escapes, but diplomatic skills if you are more spy. I kind of picture escape artist in jails and traps, or handcuffs and such. Sleight of Hand and Thievery will help as well.