With a little more than a month until the U.S. debut of "Sherlock" Season Four, PBS is teasing the return of the wildly popular detective series with a batch of new images.

In one of the photos, Benedict Cumberbatch's Sherlock Holmes directs a perturbed, or possibly perplexed, look at Baby Watson, held lovingly by his dad (Martin Freeman), standing alongside his wife Mary (Amanda Abbington).

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The images give fans a look at Toby Jones' Culverton Smith, whom executive producer Steven Moffat said is "the darkest villain we've had."

"There was always something charming and engaging about Moriarty," he said. "There was something fascinating and actually amoral, rather than immoral, about Charles Augustus Magnussen. This guy is the purest evil."

The photos also provide a glimpse at Mrs. Hudson (Una Stubbs) and Mycroft Holmes (Mark Gatiss), as well as a behind-the-scenes look at filming with Sherlock's new bloodhound companion.

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The Season Four trailers indicate the series will pick up right after the death of Season Three villain Magnussen, and could possibly deal with the return of Moriarty, despite his apparent death.

Season Four of "Sherlock" debuts Jan. 1, 2017.