‘Sherlock’ Season 4 spoilers, plot details, airdate: What to expect when Benedict Cumberbatch, Martin Freeman, cast return for new season

Filming for "Sherlock" Season 4 starring Benedict Cumberbatch (Sherlock Holmes) and Martin Freeman (John Watson) has officially begun. Meanwhile, the show creators have a lot to say about it and are dropping exciting hints. Read on for the detailed scoop.

[Spoiler alert! This article contains spoilers for "Sherlock" Season 4. Do not read further if you don't wish to know about it.]

Fans must brace as "Sherlock" is expected to be back on television soon. After starring in the special New Year episode "The Abominable Bride," Cumberbatch and Freeman along with other cast members will reprise their respective roles for three-episode Season 4. According to the press release on PBS' official website, the next three chapters of the series will bring "laughter, tears, shocks, surprises and extraordinary adventures" of Sherlock Holmes.

As Sherlock begins his new adventures in the Baker Street, London, John and his wife Mary begin to the learn lessons of parenting.

In the a statement published on the press release, "Sherlock" creators Steven Moffat and Mark Gatiss tease the storyline for Season 4. The showrunners hint at the "ghosts of the past" and impending tragedy.

"Ghosts of the past are rising in the lives of Sherlock Holmes and John Watson and terror and tragedy are looming. This is the story we've been telling from the beginning and it's about to reach its climax," the statement reads.

Meanwhile, the executive producer Sue Vertue promises that "it will be well worth the wait." As for Cumberbatch, he said that he is "genuinely thrilled" to be back on the sets of "Sherlock."

While concrete details regarding "Sherlock" Season 4 are yet to be revealed, fans can expect to see life-changing events for the series' character. Previously, speaking to Entertainment Weekly, Mark Gatiss hinted that the next season will deal with the "repercussions of Moriarty's (Andrew Scott) apparent return."

The airdate for "Sherlock" Season 4 episode 1 is yet to be revealed. Based on the series' previous seasons' airdate schedule, Collider is predicting that the show is expected to have fall/winter premiere in the United Kingdom. As for the United States premiere, it is expected to happen in January 2017.