Sherlock (2010)

Co-created with Mark Gatiss, this is the obvious gateway: Benedict Cumberbatch's Holmes and Martin Freeman's Watson in present-day London, with text messages and clues shown on screen rather than cut away to a phone. Each of the 13 feature-length episodes is a puzzle box in the purest sense, and Moffat's A Scandal in Belgravia won him a BAFTA Craft award for writing. The Victorian special, The Abominable Bride, is a treat for structure fans. Fair warning: the fourth and final series had a mixed reception, with the cleverness starting to outrun the mysteries, so treat it as an epilogue rather than the peak.