Three men abduct and keep a family tied up and gagged in the living room. Two of them dig the basement while the third one watches the family. The men find a box and decide to take a peek inside. The two men and the family immediately die. The Fringe Division investigate the case and Walter performs an autopsy on the bodies. Soon he finds that they die because they have been exposed to an ultrasound signal. Walter receives an envelope from William Bell's lawyer as inheritance and he discloses to Astrid what William left for him. Meanwhile the alternate Olivia and Newton, who had hired the men to find the box and bring to him, plot a scheme to retrieve the box. Then they set in motion a Machiavellian plan.

The Fringe team attempts to find out what process enables people to become lighter than air and float. Peter and Olivia deal with trust issues in their relationship, while Walter becomes increasingly obsessed with retrieving William Bell's consciousness from beyond the grave.