Ellen loves Link and James. Her older brother and his best friend are the only company she ever wants. She knows they fight, but she makes it a policy never to take sides. She loves her brother, the math genius and track star. She is totally, madly in love with James, his face full of long eyelashes and hidden smiles. "When you grow out of it," James teases her, "you will break my heart."

Ellen knows she'll never outgrow it. She'll always love James just the way she'll always love Link. Then someone at school asks if Link and James might be in love with each other. A simple question.

Link refuses to discuss it. James refuses to stay friends with a boy so full of secrets. Ellen's parents want Link to keep his secrets to himself, but Ellen wants to know who her brother really is. When is curiosity a betrayal? And if James says he loves her, isn't that just another way of saying he still loves Link?

My Heartbeat is a fast, furious story in which a quirky triangle learns to change its shape and Ellen, at least, learns the limits of what you can ever know about whom you love.