The Sword Thief (Peter Lerangis)

Summary: Amy and Dan Cahill have been located once again, this time in the company of the notoriously unreliable Alistair Oh.  Could they have been foolish enough to make an alliance?  

Spies report that Amy and Dan seem to be tracking the life of one of the most powerful fighters the world has ever known.  If this fearsome warrior was a Cahill, his secrets are sure to be well-guarded...and the price to uncover them might just be lethal.  (from goodreads.com)

Where can I find it?: Lower/Middle School library, Lithgow building

Tags: Code and cipher stories; Brothers and sisters; Japan; Cahill, Dan (Fictitious character); Cahill, Amy; Adventure stories; Orphans; Detective and mystery stories