Shortly after slipping out of Twilight's new school on account of it's boring lessons, the Young Six spend some quality time hanging out in the old Castle of the Two Sisters, deep in the Everfree Forest. With plenty of food provided by their friend Sandbar, they settle in for the night, swapping stories about their lives.
Unfortunately, one of Sandbar's stories involves the attack on Canterlot by the late Storm King.
This brings back some traumatic memories about Silverstream's own encounter with Anonymous - one of his commanders - during his separate attack on Mt. Aris, and how she only just barely managed to escape his clutches. And although Sandbar understands all too well what she's been through, the rest of her friends are in for quite a shock when they hear her recount the harrowing experience.

A little thing written in a few days to shake off some pretty severe writer's block, with the initial excuse of making it a Halloween special.
Takes place during the Season 8 premiere, School Daze.
Reading Rider on the Storm is strongly recommended if you want any idea about what's going on here. I'm told it's a fun read.