Were they animals... angels... or aliens?

When Roger Westwood woke up early one spring morning, he never expected that his life would change forever that day. Then he saw a strange explosion of light shatter the dawn sky. What followed was even stranger. A wild child, a boy as wild and strong as a wolf, burst out of the woods and into Roger's life.

Although the boy, who was the same age of Roger, could not even speak, Roger's mother adopted him anyway. Then the Westwoods heard of another wild child, this one a girl, who was languishing at the country hospital. They took her in as well.

But, Roger is confused yet intrigued by these children. First of all, who are they? More importantly, what are they?