High school junior Marissa McDonald is out running one day when she stumbles upon a heart-shaped balloon stuck in a tree. Attached to the balloon is a note from a young boy to the brother he recently lost; but seeing how it never reached its heavenly destination, Marissa decides to take matters into her own hands and do whatever it takes to return this letter to its author.

This challenge is incredibly important to Marissa because it’s also very personal—as she had recently lost her mother to cancer just a year ago. Despite the fact that she’d sent her own letter attached to a balloon, Marissa has never properly grieved. She won’t even talk about the fact that she’s lost her mother and her brother abandoned her when she needed him most. Only her caregiver, her grandmother, and her best friend Zoe know how much she pushes through the pain using running as an outlet for her grief.

Justifying her reasoning for returning the balloon as a simple act of kindness, she embarks upon the journey of reuniting the letter and the boy. That’s how she meets his older brother and only then does the wall she’s built up to protect herself begin to crumble. Not only is he a kindred spirit, grieving his own loss, but there is an instant spark between them. Despite their blossoming friendship, Marissa struggles to share her truth. This internal conflict bubbles to the surface as her life, strength and love unravel.

Heart on A String by Susan Soares is not only a compelling story of a young girl struggling to be independent and deal with a tragic loss, but also one of two torn hearts coming together. It confronts the personal process of grieving and how it is unique for everyone along with how PTSD can unfold even when it is so well-disguised it’s almost imperceptible. I love how the author shares Marissa’s experiences without delving too deeply, allowing the pace of the story to stay