Corvus Umbranox is an imperial nobel, count of Anvil, the Gray Fox, and husband to Millona Umbranox. He had been missing for ten years but is able to return upon lifting the Gray Cowl's curse and finding a new Gray Fox to lead the Thieves Guild.
When he doned the Gray Cowl of Nocturnal after becoming the previouse Gray Fox's susscessor he also gained it's curse which erases it's wearers name from history and thus no one reconised him. He'd disguise himself as someone called the Stranger and live in the abandoned house in Anvil.
Hieronymus Lex is the sworn enemy of the Gray Fox and does all in his power to arrest him. Once Corvus had obtained one of the Elder Scrolls he could remove curse, renounce his life of crime, and return to Millona Umbranox.