# Sherlock S04E03: how does the prison glass disappear?

In the Final Problem, how does the glass of the prison Eurus was held in really disappear? If it didn't exist at all, then how come the writings on the glass wall exist?

edit: I am actually looking for the 'how'. Yes, Sherlock explains that they were suspended, but is it possible? Or did the show runners knowingly didn't show us how because we would have noticed the 'how'?

• The writings are basically SUSPENDED SIGNS(without any glass behind them). There is no glass wall; just signs that look like they have been etched on a glass. Moreover, Eurus explains that she uses a throat mike that directly connects her to the speakers. When she turns it off, we can hear her talk normally(without the speakers) to Sherlock. Jan 17, 2017 at 9:08
• And even if the signs are suspended through some means, where do they go and why don't they hinder Eurus's way when she hits sherlock with her arms and jumps on him..? Jan 17, 2017 at 11:43
• Invisible threads are a classic tool for magicians. With adequate light, they are very difficult to notice. Especially if you are not looking for them and your focus is diverted by the magician. Jan 17, 2017 at 16:19
• The glass also reflects the people in the room Jan 20, 2017 at 16:54
• Exactly. Reflections are visible on several occasions, including in the centre pane where the glass "disappears". We know the signs are fake etching, but how is that centre pane withdrawn without Sherlock noticing, and how could Eurus be so certain he'd be sufficiently distracted? Feb 3, 2017 at 16:39

Found a picture (on Pinterest), of the rehearsal of the scene where Sherlock meets Eurus.

You can clearly see the sign is (actually) held in place via vertical rods running through both ends.

• so you mean the show runners knowingly 'erased' those rods just like they do when showing stunts and 'erase' the wires from which actors are carried. that's what i wanted to know. I guess the logic the writers portray here is moot now. May 13, 2017 at 9:39

This is made clear in the dialogue by Sherlock and a quick angled shot.

"The signs..you suspended the signs"

The text wasn't etched on the glass...they were (replacement?) signs suspended in place...although we do not see how they are suspended.

• that's what couldn't be followed. suspended signs? and not visible? Jan 16, 2017 at 19:10
• We don't see how the big sign was suspended...but it's clear that the text wasn't on the glass as you asked. Jan 16, 2017 at 19:14