The Secret in Sandcastles by Rachael Bloome

Two childhood enemies. One adventure-filled summer. And an unexpected romance they’re trying hard to resist…
Penny Heart likes to play it safe… in life and in love.

When she’s asked to brave her town’s most thrilling adventures to revamp their outdated guidebook, things quickly go from bad to worse. The person assigned to help? None other than her childhood nemesis.
His dimpled grin and endearing charm might fool other women, but she wouldn’t trust the notorious prankster with her potted cactus… let alone her heart.
Colt Davis has spent his entire life fulfilling his father’s dying wish. But something about being home—and the intriguing redhead who owns the local antique store—has him questioning everything.

As they tackle each adventure, and the rush of adrenaline grows to a genuine connection, will their differences push them further apart?
Or could a long-kept secret be the key to their happily ever after?