1. Lestrade hotfoots it to Baker Street.
But it’s not quite the emergency he thinks it is.
2. Watson and Mary get hitched.
… while Sherlock ponders if he will lose his best friend.
3. The stag-do bar crawl.
“443.7ml of beer, please.”
4. Which inevitably leads to…
5. But who is the Mayfly Man?
Come on Sherlock, use your powers of deduction.
6. The Mayfly Man is caught!
… and Sherlock expresses his love (and talent) for dancing.