I'm always a bit baffled by episodes that are all set-up; this one was particularly low on action. Bill: gets shot, is taken away, explores a bit, mostly waits Missy: supposed to be tested, is interrupted almost immediately, stays oddly silent at a console. The Doctor: sets up a test, gets interrupted, gives a short expository speech, then takes an elevator. It's an episode where nobody really does anything, but things happen *to* them instead. The classic series could be guilty of this as well, but that is some sloooooow world building.