Emerald Gryphon by Ruby Ryan

A priceless totem. An unexplainable transformation. And a secret he can’t keep from her for long.

Ever since finding the gemstone figurine in a cave in Belize, Ethan’s been experiencing strange sensations: chills, body aches, and a buzzing in his chest like there’s a beast trying to escape.
Which is exactly what happens when Jessica, a temp in his office, finds the figurine and presses the emerald set inside.

Now they share an impossible secret: that Ethan can shapeshift into a gryphon, a mythical creature with the body of a lion and head of an eagle. And as the one to first unleash it from the totem, Jessica is inexplicably bound to him.
But just when they begin to understand what the shapeshifting entails, they’re chased by a mysterious man with fire tattoos all over his body, who can turn into his own winged beast.

As they scramble for their lives, soon Jessica and Ethan begin to wonder: is such an ability a blessing… or a curse?