SPOILER ALERT: The following Once Upon a Time sneak peeks are especially revealing.

Courtesy of Sunday's "The Doctor," they begin with a confrontation between Charming and Dr. Whale, their first interaction since the former learned an unwelcome tidbit about the latter and Mary Margaret. See his reaction to it here:

Next, we have a meeting between Emma, Snow and Killian Jones. Or, as the pirate is forced to admit, Captain Hook. Watch him come clean about his identity in the following clip:

Finally, in a continuation on what we learned in the episode's official promo, we witness Regina and Dr. Whale and the devastating secret these two have concocted together. Look out, Storybrooke...

Matt Richenthal is the Editor in Chief of TV Fanatic. Follow him on Twitter and on Google+.