Master Song by Andrew Maloney

On a cold, stormy evening in Ireland, five teenagers suddenly find themselves lost, separated, and unprepared for a dangerous quest "beyond the Veil" into Morsden Forest, a secret world hidden from ours. There they must learn to grow, learn to trust, learn to fight, learn to sacrifice, and learn to love in order to rediscover the first of seven lost jewels that contain the ancient verses of The Master Song. Together with a myriad of the Awakened humanlike animals and plants they will battle wild beasts, wraithlike doppelgangers, and an evil power nearly as ancient as creation itself.

Will they stand strong and discover the virtues they have within themselves? Or will they, too, fall to the Corrupted?