The eighth day on the island finds Charlie in the grips of heroin withdraw. Charlie goes to Locke and asks for his drugs back. Locke tells Charlie he will give the drugs back to Charlie after he comes and asks for them three times. A little while later Jack sees Charlie going through the medicine supply. Charlie says he wanted to get something for a headache. Jack sees that Charlie has taken Diazepam which he comments is a little strong for a headache. A little later Jack asks Charlie to move his guitar and Charlie argues with Jack about it. This causes the entryway of the caves to collapse trapping Jack inside.
Flashbacks in The Moth focus on Charlie's relationship with his brother Liam who is also in Drive Shaft. Charlie tells Liam he is thinking about quitting the band. This happens right before the band signs a big record deal. Even with this good news Charlie is still not sure if he wants to continue exposing himself to the drugs and sexual deviation the band members have been taking part in. A shot time later Charlie sees Liam and some groupies together all high on heroin. In the dressing room Charlie kicks out the groupies and tells Liam he is quitting the band. Liam tells Charlie that he (Liam) IS Drive Shaft and nobody even knows who Charlie is. He tells Charlie that nobody ever remembers the bass player.
On the beach Sayid comes up with a plan to triangulate the French woman's signal. Kate and Boone agree to help. After Sawyer lets slip what has happened to Jack at the caves Kate leaves so he takes on the responsibility of helping triangulate the signal. Boone also goes to the caves to try and help get Jack out leaving Shannon in charge of his part of the third antenna. After all three antennas are powered up Sayid turns on the transceiver but before he can triangulate the signal someone knocks him out. Meanwhile, Charlie finds Locke who is skinning a boar and tells him about Jack stuck in the cave in. He also asks for the drugs back for a second time.
Locke shows Charlie a cocoon and explains that he could cut the cocoon and it would help the moth to get out but doing so would make the moth too weak to survive. Locke says the moth needs to struggle and fight to get free doing so helps make the moth stronger afterwards. In nature, he continues, people are the same indicating Charlie needs to fight during his struggle to get out of his addiction. Charlie returns to the cave in and squeezes his way in. He makes his way back to Jack but this causes the cave in to worsen. Charlie helps Jack pop his shoulder back in place. Jack asks Charlie how long it has been since his last fix indicating Jack also knows Charlie is going through withdraw. Charlie tells Jack he is okay.
Back in the dressing room, Liam tells Charlie that without the band Charlie is nothing and then leaves. Devastated, Charlie walks over to the table and tries heroin for the first time. A few years later and very much an addict now, Charlie visits Liam in Australia. Charlie tries to convince Liam to come back to Drive Shaft for a reunion tour. Liam, now clean and sober, criticizes Charlie for still being an addict. Charlie reminds Liam it is his fault he is addicted to heroin in the first place. Liam asks Charlie to stay with him he says he can get Charlie in a rehab clinic in Sydney. Charlie angrily leaves telling Liam he has a plane to catch.
As the air supply begins to run low for Jack and Charlie, Charlie sees a moth and watches it fly out of a small opening in the cave in. The two of them begin to dig and eventually free themselves. Later, Jack covers for Charlie when Hurley asks why Charlie looks so bad. And he does, makeup did a great job of getting Charlie looking like ten pounds of crap stuffed inside a five pound bag. Jack tells Hurley that Charlie has the flu. Charlie is grateful to Jack and then goes to Locke and for a third time asks for the heroin back. Locke, true to his word, gives the drugs back to Charlie. Charlie thrown the heroin into the fire and Locke proudly tells Charlie he knew he could do it. Charlie and Locke watch as a moth flies away.
