"Page 23" is the fourteenth episode of the sixth season of the American fantasy drama series Once Upon a Time, which aired on March 26, 2017.
In this episode, the Evil Queen and Regina prepare to face each other once and for all, while Emma learns the truth about what Hook did, which comes into play for Gideon as he takes advantage of this dilemma.
Believing that Snow is there, Regina returns to discover that the arrow leads her to her mirror, which she shatters into pieces.
Then, after Henry reveals that he only wanted to use the Pen to help move her towards redemption, The Evil Queen scoffs at the idea.
Unfortunately, just as Hook changes his mind and is about to leave Nautilus to return to Emma, the submarine submerges without Nemo ordering it to do so.
A hurt Emma waits at home for Hook, and realizing he won't be returning, shuts off the lights.
Josh Dallas, Robert Carlyle, and Emilie de Ravin are credited but do not appear in this episode.
[1] The title of this episode is a reference to the alternate page XXIII of Henry's book, which represents another version of Regina and Robin's first meeting.