Fans 'Sher-locked' with the new season 4 teaser

Sherlock is back! And the game is on.

Starring Benedict Cumberbatch, a 90-second clip trailing the fourth season of the British-American crime series that recently aired on BBC One, sent Twitter into meltdown as ecstatic fans shared their reactions online.

"Just Seen a #Sherlock trailer!!!! Omg!!! I never knew they were doing another!!!!!!" wrote one grateful fan.

"DID ANYONE ELSE SEE THE TRAILER FOR SHERLOCK IM SCREAMING!" another tweeted.

The teaser begins with Holmes' arch rival Jim Moriarty saying his famous line, "Miss me? Miss me?" and then flashes through a heated conversation between Sherlock and Molly.

Amidst the thrilling sounds of choppers and guns, Watson's wife Mary Morstan is armed with a handgun and opening a door.

"Everything they know will be tested" and "Everyone they know is under threat" are the two sentences that appear before we finally witness detective Holmes nearly in tears while standing inside a hospital.

Check out few of the other reactions on Twitter:

"Ok, that trailer was seriously amazing. I can't wait for the show to come back. #Sherlock"

"As if I got moaned at for fangirling at the Sherlock trailer"

"#Sherlock that 90 second trailer has me B U Z Z I N G"

"I am more excited to see the Sherlock trailer than anything else in my life! 1.1.17"

"seeing Andrew lose and a Sherlock trailer straight afterwards was far too much for my heart. it is still beating and I can't sleep."

The beloved crime drama TV series, based on Sir Arthur Conan Doyle's 'Sherlock Holmes' detective stories, is returning to Masterpiece, three years after we last got a proper season of the production.

Season 4's opening episode called 'The Six Thatchers' is set to premiere in the US and UK on January 1, 2017.