Determined to do the thing she fears most before graduation, Aven Shepard wants to tell her best friend, Liam, that she is in love with him, even though both Aven and Liam have significant others of their own.

"Before graduation, I promise to learn to trust" is what the email Lyla McAfee wrote to herself as a freshman, to be delivered right before graduation, says--but on the senior trip to Florida she discovers that what she now considers a silly sentiment may be a lot harder, and a lot more important, than she thinks.