When Mirabel's valentines fall out of her bag on the way to school, the shy little mouse panics. But those lost cards brighten some days...before making their way back to her.

Mirabel was very shy.
She'd always been that way.
She trembled at the thought of giving Valentines away.

Poor Mirabel! It’s almost Valentine’s Day and the shy little mouse trembles at the thought of giving cards away. Yet she carefully crafts her valentines, drawing a heart on every one. In the morning, Mirabel forces herself to hurry to school. But, in her nervousness, she doesn’t notice her bag becoming lighter and lighter: her valentines are falling out!

By the time she realizes what’s happened, they’re all gone. It turns out, though, that these lost valentines bring joy into the lives of all who find them. Then, with her valentines back in her pack, and some newfound friends, she musters up the courage to celebrate the holiday after all!