Part one of a two- part season- ender, and this is building up to one heck of a finale. Sherlock Holmes ( Jonny Lee Miller, right) ) is reeling at the reappearance of his former lover Irene Adler ( Natalie lie Dormer), who he thought was dead. His relief is palpable and a series ries of flashbacks establish not only their past, but also his path to addiction. Watson ( Lucy Liu) seems left on the sidelines as he lays himself bare to keep Adler safe from his shadowy but omnipresent nemesis, sis, Professor Moriarty. But could Moriarty be closer than Holmes thinks? s?