Baroness Troixmonde, aka Filibus, the mysterious air pirate, commits her thefts then retreats to the safety of her zeppelin. Filibus airship is manned by a staff of mask-wearing lackeys who instantly obey her every command. An esteemed detective sets out on her trail, and Filibus attempts to frame him as the daring villain-- all the while slipping in between male and female disguises to romance the detectives sister!