"In with a KABOOM!" is an orchestral piece on the Season 3 soundtrack.
The Others' book club meeting has just been interrupted by a series of tremors. The whole group walks outside to see what has happened. Ethan reveals his face, and another familiar character walks out of a house. In the air, a plane breaks up.
The camera zooms out to show the village we've been looking at is in a valley on the Island.
The name refers to the crash of Oceanic Flight 815, and to the season's dramatic opening.