When a specific group of guests at a wedding in Brookline, Massachusetts, suffocate from the inside out, the upsetting and disconcerting crime scene has the Fringe team investigating how the toxin was delivered and targeted. As evidence is taken into the lab, it’s discovered that the wedding ceremony was a testing ground for a weaponized science experiment. Adding to the intense lab investigation, Walter uncovers an alarming formula that reveals a link to a branch on the Bishop family tree. With the escalating threat of more deadly attacks and unexpected familial ties to the case, the Fringe team stops at nothing to prevent further catastrophic events.