It's Valentine's Day and the kids are making valentine boxes. A mysterious card arrives in Barney's valentine box, which he explains is from the Queen of Hearts. With a little imagination, Barney and his friends head off to visit her castle. They meet the Queen of Hearts and explore the castle. From making cookies and watching butterflies to making silly rhymes, there's fun in every corner. There's even a surprise Valentine's Day party organized by the Queen of Hearts, where B.J. and Baby Bop meet up with the others. The group gets dressed up nicely and they have loads of fun. Barney and the kids give a card they made to the Queen of Hearts, which she enjoys. Back at the Treehouse, Barney gives the kids Valentines cards.