At a Hearth's Warming party at Sweet Apple Acres, Tempest Shadow is shown a picture of the Apple parents. And she reveals a terrible truth - she's seen Bright Mac and Pear Butter before, as prisoners of the Storm King.
Neither Tempest nor Applejack even question that they're going to attempt a rescue. But the Citadel of Storms is a long way from Ponyville, and there's the problem of the entire army in their way...