This 'Sherlock' Season 3 Recap Is Elementary, My Dear Watson
Todd Antony/Hartswood Films

When a television series only airs three episodes every few years, it can be fairly easy to forget specific plot points by the time a new season rolls around. Such is the case with the BBC's Sherlock, which returns for Season 4 on New Year's Day 2017 — three whole years since Season 3 premiered back on Jan. 1, 2014. As such, it's completely understandable if you need a refresher before diving back in to the heady pleasures of watching Benedict Cumberbatch's Sherlock Holmes and Martin Freeman's John Watson as they tackle London's knottiest crimes. Thankfully, this Sherlock Season 3 recap is here to help with exactly that.

In its first two seasons, the BBC's modern take on Sir Arthur Conan Doyle's legendary detective had already adapted some of the character's most famous cases, including The Hound Of The Baskervilles and Holmes' final confrontation with arch-nemesis Moriarty at Reichenbach Falls. But things, if possible, got even more mind-bending in Season 3, with not only the dramatic resurrection of Sherlock himself, but also the rise of a new villain, the possible return of Moriarty, and a visit from a particularly abominable bride.

Don't feel left behind when Sherlock Season 4 premieres this Sunday; catch up on all the twists and turns you might have forgotten right here:

1. "Many Happy Returns"

BBC on YouTube

On Christmas Eve 2013, Sherlock fans were treated with an online-only mini-episode that teased the incipient Season 3 premiere. In the seven-minute video, disgraced forensic scientist Philip Anderson — formerly a bitter antagonist towards Holmes — had apparently become obsessively convinced that the deceased detective is still alive, and tried to convince Lestrade that Sherlock was out there anonymously solving cases.

In a separate plot thread, Watson received a birthday present from his former partner in the form of a video message, in which Sherlock promised that John would see him soon… and then winked at the camera. (You can watch the entire webisode above.)

2. "The Empty Hearse"

BBC on YouTube

The official Season 3 premiere finally solved the lingering mystery of how Holmes survived his fatal fall at the end of the Season 2 finale two years prior. Having secretly returned to London to help his brother Mycroft thwart an impending terrorist attack, Sherlock made his true fate known to Watson, who had moved on with his life in the meantime — including acquiring a lovely fiancée, Mary. (Naturally, John was none too happy to learn how Sherlock had deceived him.)

Through a series of flashbacks, we saw various scenarios that could have explained Holmes' survival, with one far-fetched possibility involving a bungee cord, and the apparently true solution involving an inflatable mattress, a conveniently placed squash ball, and Sherlock's helpful Homeless Network.

In the end, Holmes and Watson were able to stop the terrorist attack in time (although John had a close call in which he was kidnapped and nearly murdered via bonfire before being rescued by Sherlock), and Holmes was able to get Watson to admit how much he'd missed him with the help of a literal ticking time bomb.

3. "The Sign Of Three"

Serials Group on YouTube

At John and Mary's wedding, Sherlock became convinced during delivery of his Best Man speech that one of the guests in attendance was plotting a pernicious crime: the murder of Watson's reclusive military acquaintance, Major James Sholto. In the course of his rambling speech, Holmes recalled a couple of seemingly unconnected cases from his and Watson's past, including the attempted murder of a soldier ("The Bloody Guardsman") and the mystery of a man who would court women by posing as a recently deceased stranger before vanishing ("The Mayfly Man").

Of course, it turned out these cases were indeed connected, and they pointed Sherlock towards the murderous wedding crasher: the photographer, who blamed Sholto for the death of his brother in Afghanistan. The man used the attempted murder of the guardsman as practice, and got information on the Major's whereabouts and itinerary from the women — all of whom worked for the recluse in some capacity. With this knowledge, the detective was able to stop the killer and save Sholto's life just in time.

The title of the episode came from Sherlock's final realization, that Mary was exhibiting "the signs of three," namely increased appetite, changes in her taste, and morning sickness. Together, these signs pointed towards an inescapable conclusion: that Mary was pregnant.

4. "His Last Vow"

Serials Group on YouTube

The final episode of Season 3 introduced viewers to Sherlock's newest nemesis, Charles Augustus Magnussen, a newspaper magnate with a penchant for blackmail. In the course of his investigation into the devious villain — revealed to be the man behind Watson's kidnapping in "The Empty Hearse" — Holmes was confronted by John's new bride Mary… who shot him at Magnussen's bidding.

It turned out that Mary had a former life as an assassin, and Magnussen was using his knowledge of her past to blackmail her into disposing of Sherlock for him; but thankfully, Mary knowingly shot the detective in a non-fatal spot. He survived the wound and headed to confront Magnussen at his estate. (Meanwhile, John was understandably shocked to learn the truth about his pregnant wife, but he ultimately decided to destroy a memory stick she gave him that contained details about her past.)

Sherlock, having stolen Mycroft's laptop, offered to trade his brother's confidential information for Magnussen's evidence about Mary. The detective's real plan was to have a GPS tracker in the laptop lead the police to Magnussen's home, which they would now have cause to search, discovering proof of the villain's blackmail and putting an end to his manipulations. But Magnussen one-upped our hero by revealing that the only evidence he kept for his blackmailing existed inside his own "Mind Palace" — so instead, Sherlock would be arrested for selling state secrets, and Magnussen would go free with no hard evidence against him.

Of course, Sherlock realized the only way he could destroy Magnussen's evidence and bring the villain down once and for all: to shoot him in the head. The detective was quickly arrested for murder, but instead of being tried in court, he was sent out of the country on a dangerous mission to Eastern Europe. But Sherlock's exile was cut short when a video was broadcast all over England featuring Moriarty's face asking, "Did you miss me?"

5. "The Abominable Bride"

Sherlock on YouTube

Although technically not a part of Season 3 proper, fans were treated to one more episode before Season 4, airing as a Special on New Year's Day 2016. This episode famously transported Holmes and Watson back to their original Victorian setting — although the events taking place in 1895 were quickly revealed to be the fevered imaginings of Sherlock's drug-addled mind, as he tried to cope with and solve the mystery of Moriarty's apparent resurrection through his knowledge of an unsolved case from over 100 years ago.

The case pertained Emelia Ricoletti, who apparently rose from the dead to murder her husband hours after having killed herself in full view of a crowded street. Ultimately it was revealed that the woman pulled off the stunt with the help of the Women's Rights Movement, whose members continued to use the specter of the deceased Ricoletti to avenge themselves against other men who had wronged them.

Having finally solved this lingering mystery, Sherlock used his knowledge of the Ricoletti case to extrapolate that, much like Emelia 100 years ago, Moriarty really was dead after all — but others were continuing the villain's work in his own name and image.

Sherlock on YouTube

Find our what Moriarty's disciples are up to when Sherlock Season 4 premieres this Sunday, Jan. 1, on PBS.