I can not believe this has not been done yet.
Two masters on opposite sides of the legal spectrum; a genius detective and a genius thief. Both are hyper intelligent, ludicrously skilled at deduction, almost incapable of making mistakes and possesses a vast array of useful skills and abilities. It's time for a showdown!
Scenario 1: Lupin has sent a letter to a wealthy household where he explains that he intends to rob them of their most precious belongings. The intended victims quickly hire Sherlock Holmes to stop him.
Scenario 2: Having spent some time in prison, Lupin grows tired of incarceration and informs his jailors that he intends to escape. Sherlock is called in to make sure he stays where he is.
Scenario 3: Sherlock in hunting a criminal who has somehow offended Lupin, who decides to capture him personally. Both swear to track down the culprit before the other.
Who comes out on top in this battle of wits?