Martin Freeman and Amanda Abbington as John and Mary Watson in "Sherlock"
Martin Freeman and Amanda Abbington as John and Mary Watson in "Sherlock"

“Sherlock” season 4 episode 1 commanded laughs and ultimately tears on Monday as it hinted on a new character and said farewell to a beloved member. Benedict Cumberbatch, Martin Freeman and Amanda Abbington return for the UK series’ season 4 premiere “The Six Thatchers.”

‘Sherlock’ season 4 episode 1 spoilers ahead. The following article reveals recap of the show.

What started out as an almost faithful modern rendition of Sir Arthur Conan Doyle’s “The Six Napoleons” ended in heartache as the BBC series delved into Mary Watson’s (Abbington) past. The good news is viewers have been let in on Mary’s mysterious past. The bad news is that Mary died near the end of the episode.

A third Holmes brother is heavily hinted on as well.

Moriarty’s presence wasn’t physical but very much felt in the episode. He was still dead, as Sherlock Holmes (Cumberbatch) has insisted. However, Sherlock knew that Moriarty would still strike, and he planned to wait for it by just doing his regular, case-solving stuff.

While solving the mystery of a week-long dead son, he chanced upon a stolen Margaret Thatcher bust, which he found odd. Someone was stealing and smashing the Thatcher busts from different homes because he wanted to recover an item he hid inside one of the six sculptures years ago.

The thief turned out to be Mary’s former colleague, Ajay, and the item inside the bust was a memory stick containing information about Mary and her past as a freelance spy agent. Mary also had a similar memory stick, which she gave to John Watson (Freeman) and which he subsequently destroyed. It contained data on each of the four members (A.G.R.A.) so they couldn’t turn on each other. A failed mission in Tbilisi ended their group, with Mary thinking she was the only one who survived.

Sherlock confronted Mary with his discovery, promising he would make her safe no matter what. Mary, after drugging Sherlock, ran away to random places around the world, following clues. Sherlock and John were still able to catch up with her after placing a tracking device on the memory stick. Ajay followed Sherlock, and therefore was able to be reunited with them. He thought Mary betrayed them. While being tortured, he heard his captors whispering “Ammo” and talking about an “English woman” on the phone, which he thought referred to Mary.

It wasn’t Mary, though; it was government clerk Vivian who betrayed the group. Sherlock found her in the London Aquarium, forcing her to confess. Upon being cornered, Vivian pulled out a gun and shot at Sherlock, but Mary jumped in the way to take the bullet for herself. She died just in time for John to appear and for her to thank her husband for providing her with a normal life.

And as Sherlock promised to protect her and failed, Mary’s death has created a rift between him and John. John, who was revealed to have had flirted with starting an emotional affair with another woman, is now left with an infant daughter, Rosamund Mary Watson, without a wife.

Mary is really dead

Unlike Sherlock, Mary won’t be coming back from the dead anymore. Co-creator Steven Moffat confirmed her death is permanent.

“We’re not playing games. She’s dead,” he told EW. And yes, the rift between Sherlock and Watson will get “worse.”

Save John Watson

Mary knew her past would haunt her, and the only way for agents like her to retire is by permanent retirement. She left Sherlock a video message, which Sherlock found after her death. In the video, she gave her friend a case, which she said would be the hardest he would take. “Save John Watson,” she implored.

Sherrinford, the third Holmes brother

It has been hinted on in the past season that Sherlock and Mycroft Holmes (Mark Gatiss) have another brother, and there were a few theories on who that might be. There was no confirmation or even acknowledgment that there really exists another Holmes brother from the show, though, not until a latter scene in “The Six Thatchers.”

Read related: ‘Sherlock’: The problem with Tom Hiddleston playing a third Holmes brother

Mycroft has previously vaguely mentioned about another brother without mentioning a name. In this episode, however, he has uttered “Sherrinford,” the name subsequent “Sherlock” authors gave to Mycroft and Sherlock’s eldest brother.

It may mean the show will introduce Sherrinford in the coming episodes, or at least acknowledge that the Holmes brothers indeed have another sibling.

“Sherlock” season 4 airs on BBC Australia.

Watch ‘Sherlock’ season 4 episode 2 ‘The Lying Detective’ trailer