"Sherlock" Season 4 continues to look dark in the series' latest preview.

When we pick up with the adventures of Sherlock Holmes (Toby Jones.

The preview offers interesting glimpses at the episodes to come. We see the titular detective in strange circumstances n various intriguing scenes: in front of a burning house, sprawled out on a table, and clutching a gun. Yet, after all the darkness, the trailer ends on an unexpected note: Sherlock looks straight into the camera and declares, "I love you."

"Sherlock" premieres on PBS Masterpiece on Jan. 1.