Daphne is beginning to embrace her destiny as the cypher and is discovering the power of her musical ability. Along with her friends, she is determined to find the Key of Hades and save her world from the Keres. Haden has chosen Daphne and what is right over power, but is struggling with his feelings for Daphne and how to tell her. Time is running out to find the Key before the spring equinox, and with Skylords in Olympus Hills and a possible traitor in their group can Daphne and Haden succeed.
The Eternity Key is the really enjoyable sequel to The Shadow Prince. It is fast paced, and I found the story more interesting than the previous book. This book has more action and romance, and while a bit predictable I wanted to find out what was happening next.
Daphne feels like she has the weight of the world on her shoulders which leaves her feeling really stressed in this book but she is less naïve and still a very nice, if a bit too perfect, person. Haden has accepted who he is and the choices he has made, he is more human in this book and is very protective. We get Tobin’s POV in this book and we get to understand him more and his determination to find his sister.
I really liked this book and I am looking forward to the next book in this series, as this did end on a cliff-hanger. I would recommend The Eternity Key to fans of the first book in the Into the Dark series The Shadow Prince.