S1·E7 The Adventure of the Sussex Vampire Lot

A mysterious and somewhat theatrical vampire is crashing computer grids, swimping codes, invading locked vaults, and causing panic in New London. The only clue is video images of the devil grinning into the camera as he crushes a computer disk in his hand. Lestrade pursues the Sussex vampire with her usual (destructive) aplomb, which rather amuses the detective. Diedre--who has a unique female perspective on things that Holmes cannot for all his smarts manufacture--notes an interesting quirk their foe has while watching hours of old vamp flicks and tapes of the Sussex vamp's little disk-breaking show. Holmes, Watson, and the Baker St. Irregulars pursue the data-sucking fiend into its sewer lair...and meet up with an old ""friend"" of Holmes', who is also looking into the vamp matter.