Twelve-year-old Jack Harket is a street urchin living on the London docks. A merchant ship sales into port at twlight. Aside from a flock of enormous black bats that flies from its hull, there's only one living soul on board, a young stowaway named Benedict Cole. The two boys find themselves on the same side of a deadly struggle facing a plague the likes of which London has never seen.

"A working partners series"--p. 4 of cover.