The floor of the Looking Glass is covered in the blood of Mikhail and the Ladies Auxiliary. Charlie is covering the bodies when he tells Desmond that there is diving equipment over there. He tells him to take care of that while he goes to type in "Good Vibrations." He stops Desmond to ask, "Hey, Des, any flashes?" Desmond shakes his head, "No." Charlie smiles, "Good. Then I'll meet you back here then." He walks into the signal room and stares at the key pad for a minute, hums the tune to "Good Vibrations" and types it in without practicing, without testing which tone goes with which number, and without screwing up a single note. Damn! He is a good musician! Or phone dialer. The light goes off and Charlie shrugs, "So much for fate." As he turns to leave he hears a beeping sound and looks to see a light indicating that there is an incoming transmission. Instead of ignoring it and, you know, not tempting fate, Charlie decides to answer the call. Chucklehead. He pushes the button and a fuzzy picture emerges and a voice shouts across the wire, "Hello? Can you hear me?" Charlie replies excitedly, "Yes! I can hear you!" The picture becomes clearer and we see that it is Penny. She asks who he is, and Charlie explains that he is a survivor of Oceanic Flight 815 and that they're on an Island, but he can't tell her where the Island is. He asks who she is and she replies, "I'm Penelope." Charlie, displaying more brainpower than I previously thought him capable of, puts two and two together and shouts for Desmond. Penny hears and gets all excited. Charlie says that Desmond is there and he's fine and everything. Then he asks if Penny is on her boat. She asks, "What boat?" Charlie replies, "You know your boat? Eighty miles off shore? With Naomi?" Penny is confused, "Who's Naomi?"
As Charlie lets this realization sink in, Desmond is hurrying back to the signal room when he notices that Mikhail is gone. Desmond starts running towards Charlie, but Charlie has already figured out that Mikhail is not where he is supposed to be since Mikhail is outside the station, tapping on the window. With a grenade. Charlie realizes what is about to happen, but instead of running out of the room and slamming the door behind him, he stays in the room, locks himself in, and stands there while Mikhail detonates the grenade, shattering the window, and quickly filling the room with water. Instead of just writing chucklehead, chucklehead, chucklehead, I'm going to assume that Charlie was too panicked to think straight and opted to sacrifice himself to save Desmond. It seems sweeter, sadder, and less idiotic that way. As the room fills with water, Desmond pounds on the window with a fire extinguisher trying to break the glass. Charlie manages to keep his wits about him enough to write on his hand (with a Sharpie, of course!) the incredibly important fact that it is "Not Penny's Boat." He slams his hand against the window and Desmond gets the message. Desmond tears up as Charlie makes sure he understands. He floats away from the window and crosses himself as he crosses over to the great unknown. On land, Aaron cries as Charlie dies. Claire tries to comfort him, but when Naomi asks what's wrong, Claire says that Aaron is just scared. Naomi says she doesn't blame him. Just then her phone chirps and she pulls it out to read that the Channel is Open. She asks Claire, "What's your boyfriend's name?" Claire looks confused so Naomi clarifies, "The rock star who swam down to the station?" Claire is all, "Oh that boyfriend! Charlie. Why?" Naomi answers, "Because he just got us rescued." So Charlie's great sacrifice was worth it. I'm sure Desmond will sleep easier knowing that.