The conversation gets loony when Dr. Sanders speaks of Space Agent UD-4126 and omens of the Cullen virus leading to the apocalypse.
Elizabeth learns that Dr. Sanders had created an antidote for the virus and the team suspects that he was working with another doctor from outside the mental institution.
Elizabeth pays Dr. Sanders another visit and noticing the nurse's ID badge number, it turns out that UD-4126 leads to one Dr. Nikolaus Vogel (Brennan Brown).
Dr. Vogel gives up the names of 5 people involved in a prison plane transport, all airport employees infected with Cullen.
[3] Jason Evans of The Wall Street Journal gave a positive review of the episode: "Wow… just wow!
This one delivered a couple of key reveals and certainly set stories and characters up for what could be a crazy, deadly finale.
Yet, this second half of the season has been so content to just push the goalposts to the next week that there's no guarantee that the crazy and deadly will ever come".