Ghost in the Machine

In the 1950s, Central City's guardian was Desmond Powell, who fought crime as "The Nightshade". His nemesis, a criminal mastermind known as "The Ghost", is believed to have died after a confrontation, causing a guilt-stricken Powell to retire. However, the Ghost has in fact preserved himself in suspended animation and resurfaces in the 1990s, where he hijacks Central City's power grids and holds the city for ransom, forcing Powell to return to action and join forces with the Flash.