Apple TV+ put the cast of 'Severance,' including Adan Scott and Patricia Arquette, in a glass box at Grand Central Station to promote Season 2.

The pop-up began when a large glass box appeared in Grand Central's Vanderbilt Hall, containing a replica of the four-seated desk from Lumon's Macrodata Refinement department. Hired actors playing Lumon employees sat at their desks, doing Lumon things (by which I mean, sorting numbers while not having a clue what said numbers mean).

Here’s a quick refresher on where things stand with Mark, Helly, and the gang The second season of Severance, which debuts tonight on Apple TV+, proves that the corporate sci-fi drama has still got it.

The acclaimed Apple TV+ series is making its long-awaited return. A second season was filmed over three years.

Here's what you should remember from the first season of "Severance" and how certain moments and symbols could foreshadow what happens in Season 2.