When a couple of scammers hold young Alice Faulkner against her will to discover the whereabouts of letters whose dissemination could cause a scandal affecting the royal family, Sherlock Holmes decides to take over the case. (Considered lost, a copy was found in 2014, in the vaults of the Cinémathèque Française.)
Coke Ennyday, the scientific detective, divides his time into periods of "Sleep", "Eat", "Dope" and "Drinks". In fact, he overcomes every situation with drugs: consuming cocaine to increase his energy or injecting it in his opponents to incapacitate them. To help the police, he tracks down a contraband of opium (which he eagerly tastes) transported within "leaping fishes", saving a "fish-blower" girl from blackmail along the way.
The mysterious air pirate Filibus steals from the rich and then retreats to the safety of her airship, which is manned by a staff of mask-wearing lackeys who instantly obey her every command. When an esteemed detective sets out to investigate the thefts, Filibus attempts to frame him as the burglar, while also slipping between male and female disguises to romance the detective's sister.