With a chill in the winter air, teen sleuth Tessa Wright discovers a heartwarming mystery this Valentine's Day.

Beloved downtown Greeneville Heights is aflutter with couples flocking to high-end jewelry store Carmichael's for the perfect sparkly gift. Following the trail of hearts, Tessa and her valentine Mason investigate the vintage charm bracelet dangling from her wrist. The gold keepsakes link Tessa to the past, and she is sent on a journey to ponder a forgotten life of love and adventure.

A volunteer endeavor at Sunny View Senior Center gives the TSLR Detective Agency its next lead. While the girls create a majestic mural for the residents, Skylar's starlet grandmother plays Cupid. But with a secret admirer on the loose, leaving behind pink "crush" carnations, Tessa once again finds herself on locker-stakeout duty in a case that is all too familiar.

Tessa's cross-country ankle injury may have healed, but not all injuries are physical. Fortunately, sweetheart Mason has a plan to get her back on track in time for the spring running season. As the end of the school year closes in at Greeneville Middle, the girls embark upon their biggest adventure yet: high school.