The event starts at 6pm at the storied library's 10 1/2 Beacon Street building. The good news is that it's free if you're a member; the bad news is that it is $15 if you are not, but I promise it will be worth it. There will be a reception afterward.
Either way, they ask you to register here.
Don't live in Boston? Don't despair. My full event schedule, updated regularly, can be found here.