Claire finally loses herself in the hum as the outside world closes in on the group. One last group session ends in tragedy.

Unable to experience the hum the way the others can, and increasingly guilty about her relationship with Kyle, Claire has a crisis.

Claire and Kyle discover a group of other people who not only can hear the hum but want to embrace it. However, Kyle's mother finds out about their meetings.

When Claire starts hearing an incessant rumbling sound, no-one seems able to help – until her student Kyle claims to also hear the noise.