What He Thought Was Lost

This is set several years after The Shattered Castle. Jaron Eckbert has been acting a little strange. Tobias and the rest of the gang must figure out what the problem is, before it's too late.

Meanwhile, a messenger from Avenia arrives. His message states that King Kippenger has found a prisoner that Carthya might have an interest in.
Who is this prisoner? And what has contributed to Jaron's strange behavior?

I own Hazel and the plot. All other credit goes to Jennifer A. Nielson