Nurse Redheart takes on a personal quest from the Princesses, Celestia and Luna. She must travel to another world in search of something that the Princesses refer to as "Their Heart." Travelling to the other world Nurse Redheart must find a way to blend in with the humans in order to find that which she is searching for. Lyra, who is already there and through her studies has learned much about humans may just be able to help.

The Sun and Moon,
United, They are our strength,
Day and Night, They Watch over us,
Within the sun's golden light, the oldest, Celestia protects and guides us,
Within the moon's pale silver light, the youngest, Luna protects and guides us,
They smile as They see us enjoying life, safe under Their protection,
We know not that They wear this as a mask,
Hiding away great agony within Themselves,
Something priceless and precious to Them,
Stolen by the cruelty of Fate,
Taken from Them before Their very eyes,
Never to be seen again,
Lost and forgotten,
As memories fade with time,
Their hearts cry out,
Desiring to be healed,
Wanting to find that which has been lost.

A few days have passed since Princess Celestia and Luna, found their long, lost little brother, Astrello. It is morning and Rainbow Dash is flying through the clouds when he sees Princess Celestia and Luna out on the balcony smiling. They wave happily at Rainbow and she waves back. Calling out to her the Princesses wait for her to come. Rainbow flies down and land beside them. They tell her that she and her friends are invited to come to the palace for a special surprise. Rainbow smile and takes off to tell the others.