John Hannah is to star as a drug dealer alongside fellow Brit Jonny Lee Miller in US Sherlock Holmes update Elementary.
Hannah – seen recently on the other side of the law as DI Jack Cloth in crime spoof A Touch of Cloth – will play Holmes's former supplier Rhys, who travels from London to New York to seek the detective's help.
Meanwhile, fans can also look forward to the first appearance of Holmes’s arch-adversary Moriarty.
Elementary executive producer Rob Doherty said he was looking for a “tremendous actor” to play the key character, who will feature before the end of the current series as the story becomes more "serialised".
“[His appearance is] probably in the immediate future, but we have a few more weeks before we have to sweat that,” said Doherty.
Another canonical Holmes character set to make an appearance – if only in flashback – is Sherlock's former girlfriend Irene Adler who, in Elementary's version of events, was murdered by Moriarty in London before the detective made his move stateside.
“She’s an important element of Sherlock’s backstory. I’d love to have a face to that name," said Doherty, speaking at the Television Critics Association press tour at the weekend.
"We’ve talked about doing a flashback show [to] see why Sherlock would be drawn to this particular woman... so we definitely want to meet her. In that sense, you will see a living, breathing actress reading lines as Irene."
Elementary is currently in hiatus midway through its first season but has been extended to 22 parts by US network CBS. The series returns to its UK home of Sky Living in February for an uninterrupted run, which will see later episodes airing just days after they premiere in America.