January will be quite a month for "Sherlock" fans as they will be ringing in the New Year with its season 4 premiere. And for the following two Sundays, the rest of the episodes will be shown.

Unlike the third season of "Sherlock," which had a somewhat sporadic schedule, the fourth season will regularly air on Sundays, starting on New Year's Day, Jan. 1, reports RadioTimes. The premiere episode is titled "The Six Thatchers," and it will be followed by "The Lying Detective" set to air on Jan. 8. The final episode of season 4 will air on Jan. 15, although the official title has yet to be revealed.

Last week, a new teaser trailer for the upcoming season was released online. Rather short and uneventful, it did not provide a lot of hints as to what the new season may bring at first glance. The odd clip, however, has since been analyzed by fans and publications alike. And it has revealed a few interesting easter eggs.

According to Observer, the yellow smiley face sprayed on the wall of Sherlock's flat can clearly be seen through a reflection, but this was not the case before. In addition to that, Mycroft's umbrella can also be spotted by the fireplace. These may be crucial hints about the plot of the new season.

Meanwhile, other clues have also been pinpointed by the Independent. According to the news site, a close-up look at the music sheet in the water reveals its title, "Miss Me?" Avid fans know that those were Moriarty's very words in the season 3 finale which caused Sherlock to question what he saw on the rooftop the day Moriarty shot himself. 

Apart from that, a Persian slipper can also be seen floating in Sherlock's flooded flat. The publication points out that the famous detective hid his tobacco in a Persian slipper in the story, "The Musgrave Ritual." Fans know that Sherlock has struggled with drug use and dependency in the past, so this could be another clue that the problem will be back.

"Sherlock" season 4 will premiere on Jan. 1, 2017 on PBS Masterpiece. The specific time slot has not been announced.