The Moonstone Chamber is a location from the 1985 animated series She-Ra: Princess of Power.
She-Ra: Princess of Power
The Moonstone Chamber is a sacred place inside Castle Bright Moon which is forbidden to enter for anyone except Queen Angella. The only other person who has a key, striclty for emergencies, is Angella's daughter Glimmer.
The Moonstone is an ancient gift that was presented to the Royal family of Bright Moon many years earlier. It keeps the palace protected day and night but without the Moonstone in place, Bright Moon's defences are greatly weakened.
When the Moonstone was removed from it's pedestal by False Face (disguised as Prince Highcliff), it could only be restored in a bond from generation to generation. Therefore, Angella and Glimmer had to work together, holding hands to restore the strength of the Moonstone to Bright Moon.