'Once Upon a Time' Preview: Operation Mongoose (VIDEO)

By Rickey ·

Here's the video preview and synopsis of Once Upon a Time Season 4 Episode 21: "Operation Mongoose" on ABC.

Two hour season finale!

'Once Upon a Time' Preview- Operation Mongoose (VIDEO)

Once Upon a Time 4x21 Promo "Operation Mongoose"

Air Date:

May 10, 2015

Official Synopsis:

Season Finale!

For more previews and recaps, check out Once Upon a Time

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