Sherlock series 3 episode 2 The Sign of Three programme guide

Sunday 5 January 8:30pm BBC1

Sherlock faces his biggest challenge of all – delivering a best man’s speech on John’s wedding day. But all isn’t quite as it seems. Mortal danger stalks the reception – and someone might not make it to the happy couple’s first dance. Sherlock must thank the bridesmaids, solve the case and stop a killer.

Radio Times Choice

Writers Steven Moffat, Mark Gatiss and Steve Thompson have obviously taken their feet off the pedals and decided to freewheel down a steep hill in The Sign of Three, just to see where they end up. It’s a frenetic, curious ride, full of feints and dead ends and lots of double-backing – by the end you might feel both puzzled and exhausted. It’s audacious, to say the least. The tone is very different from usual, too – overtly comical, almost farcical at times – as we join Sherlock on the wedding day of his faithful Boswell, Dr John Watson (Martin Freeman).

The great detective (Benedict Cumberbatch) is agonising over his best man’s speech. For someone so supremely gifted who is so used to grandstanding, public speaking terrifies him. There’s little point in trying to sum up a plot that gallops in so many directions, just hang on tight and DO try to keep up.

Radio Times TV editor Alison Graham