(spoilers)
So it looks like the sisters' weekend camping trip we saw back in Season 3 has now become an annual tradition. Some things have changed (like Rarity settling for a more modest tent and packing not quite so heavily) while others are still the same (Scootaloo still apparently has an intense fear of being out in the woods). However, some kind of massive bug infestation forces the six ponies to flee their camp and take shelter inside a cave. While they wait for things to improve, Applejack, Rarity, and Rainbow Dash each decide to share their favorite legend. (I'm afraid I can't immediately remember their names, since I've currently seen the episode only once.)
Applejack starts off with a legend about an earth pony stallion who wished to join a group of brave warriors, but was never taken seriously due to how scrawny he was. But then when the nearby volcano erupts and threatens the village, he jumps into action by trying to dig a trench to divert the lava flow. Obviously, this would seem like an impossible task with how little time he had, but then some strange force of magic suddenly gives him the strength to finish the task just in time, saving the village and earning the right to join that warrior group.
Rarity next tells the legend of of a beautiful unicorn mare who, after being away studying at a magic school, returns home to find the once beautiful town has been impoverished by the new empress, who also happens to be a formerly close friend of hers. She confronts the empress, who was so jealous of her beauty that she tried a spell on herself that ended up horribly backfiring, thus corrupting her into removing beauty from everywhere else. After a magic dual, the empress is defeated, and the mare restores beauty to the land, even though it comes at the cost of her own beauty.
Rainbow Dash then tells the legend of a pegasus stallion who was part of a military legion trying to make their way back home, but some dragons wouldn't let them pass and they end up capturing some of his comrades. Against his commander's wishes, he wants to rescue them, so he decides to distract the dragons and lure them out of the cave so the rest of the legion can rescue their fellow soldiers. He manages to fly faster than the dragons, and after the legion sets a trap of a massive storm cloud, the dragons are sent back, and the entire legion is able to continue home.
After the stories are finished, the six ponies manage to find an alternate route to their destination, and despite the earlier infestation, they agree that the camping trip was still enjoyable thanks to all those stories they shared.
I liked this episode quite a lot. I was especially fascinated to see the pony interpretations of the different settings for each of these legends (Norse for the first, Ancient Chinese for the second, and Roman for the third). It certainly does a great job of expanding the pony world beyond Equestria, and I would very much like to see more of this kind of world-building content in some future episodes and seasons.
(end spoilers)