Fishstix1
Princess Furn, princess Bear, and prince Robin were all captured by witches when they were playing in the woods. The eldest sibling escaped to inform the kingdom. When she tells the king and queen they say she can't go to look for them and send out a search party. When the search party never comes back the kingdom builds a wall so no one could ever get in or out. Furn never saw her siblings again until four years later...
(P.S. I wrote this for like 8-11 year olds but the youngest I could do was 13... so don't judge.)