By Caroline Dowse @toongirl83

It's a brand new year, which means one thing - a brand spanking new episode of Sherlock. Not just one episode either, but a whole series. Great news for us Sherlock fans.

Called The Tale Of The Six Thatchers, it picked up where the last episode, The Abominable Bride, left off, and featured Sherlock trying to catch a vandal who was smashing up busts of Margaret Thatcher. And no, it wasn't Arthur Scargill. Sherlock discovered the first bust while investigating an unrelated case and became convinced it was part of something bigger. After that more smashed busts turned up, along with a dead woman. So far, so confusing.

John and Mary Watson, meanwhile, were enjoying domestic bliss with their new daughter, Rosemund, but you sensed it wasn't going to last. And sure enough, it didn't.

When Sherlock finally caught the vandal, a guy called AJ, he discovered a connection to Mary. Mary had once been an assassin and AJ was a member of her team, Aggro (No, really). When they'd been sent to carry out a job at the Georgian embassy, Aggro were attacked and AJ and another member were captured while Mary got away. Realising they'd been betrayed, AJ blamed Mary and wanted her dead. He also wanted a memory stick that he'd hidden in one of the Thatcher busts that contained details of his past.

Fearing for her and her family's lives, Mary fled to the Middle East using a variety of disguises and planning her every move randomly, using a dice...or something. I don't know, I lost it a little bit at that point. Anyway, Sherlock tracked her down, and after a gunfight that killed AJ they headed back to London to find the real traitor. It turned out to be a secretary who had appeared in the first scene and who everybody had probably forgotten about. I know I had. The secretary, Vivienne, had been running Aggro's missions alongside her filing and shorthand duties and earning a nice bit of money on the side to pay for a cottage in Cornwall. During a tense stand-off at an aquarium she tried to shoot Sherlock, only for Mary to jump in front of him and take the bullet. She died, which was a shock twist that I don't think any of us saw coming.

This was a great episode, but it wasn't without his faults. There were a few pointless parts, like Watson daydreaming about texting an attractive woman he met at a bus stop. It was odd and didn't really move the plot along. Also, it would be nice to understand why Sherlock does some of the things he does. Sometimes he just seems too enigmatic - but maybe that's the point.

There were some grumblings on Twitter that it was too complicated to follow, but I didn't think it was too bad compared to previous episodes. It was better than The Abominable Bride, which was basically about Sherlock being off his face on drugs for an hour and a half. Next week we get our first look at Toby Jones as the new villain, Culverton Smith, and I for one can't wait.