From the back of the book:
Defying orders, Rebel agents launch a desperate search for a missing friend. What they find could shatter the Rebellion forever.
Rebel Agent Tiree is missing. He never made it to the rendezvous point. Rebel High Command cannot spare the men to launch a full scale search; Tiree is on his own. One group of heroes owes Tiree more than they can ever repay, however, and they vow to find him.
Retracing Tiree's trail, the Rebels go to the planet Questal. Tiree was on an unsanctioned mission there, hot on the trail of a rumored weapon of fearful proportions. Then he disappeared.
Now something is hunting the Rebels.
Can they avoid Tiree's fate, rescue their friend, and save the Alliance?