In the Dark

 is the sixth episode of the second season of Under the Dome.

Synopsis
Barbie and Sam investigate the tunnel behind Melanie's locker at the school, but an explosion from a booby trap causes a cave-in and cuts them off from Junior. Meanwhile, a dust storm brought on by the acidity of the red rain overtakes the town. Julia chooses to help Barbie rather than focus on the weather crisis, while Big Jim attempts to regain the support of the townspeople. He is initially unsuccessful, but eventually convinces the people to build a mist-dispersing windmill, which calms the dust storm. Below ground, Barbie and Sam explore a huge cave system, eventually reaching a seemingly endless chasm, which they reason must lie outside the boundaries of the dome; Lyle's supplies are found at the site, but he remains missing. The two reminisce about the past, and Barbie eventually sees the scratches on Sam's shoulder and realizes that it was Sam who murdered Angie, and has been hunting the four hands. He warns Barbie that the dome will only fall when the four are dead, and overtaken by the hopelessness of his situation, leaps into the chasm. Julia and Rebecca use explosives to blast through the cave-in, rescuing Barbie. Meanwhile, Joe, Norrie, Melanie and Junior hide from Lyle, whom they believe is trying to kill them, and after recovering the egg from the lake, activate it and are showered in pink stars. The stars take on a shape that is familiar to Melanie: an obelisk standing in her old hometown, Zenith.