The fourth series begins with the nation’s favourite detective, the mercurial Sherlock Holmes, back once more on British soil, as Doctor Watson and his wife, Mary, prepare for their biggest ever challenge - becoming parents for the first time.

Sherlock Holmes and Dr. Watson find themselves in 1890s London in this holiday special.

As U.S. troops storm the beaches of Normandy, three brothers lie dead on the battlefield, with a fourth trapped behind enemy lines. Ranger captain John Miller and seven men are tasked with penetrating German-held territory and bringing the boy home.

His Dark Materials is set in an alternative world where all humans have animal companions called dæmons, which are the manifestation of the human soul. The series follows the life of young Lyra (Dafne Keen) who is an orphan living with the scholars at Jordan College, Oxford. As in Pullman's novel, Lyra discovers a dangerous secret that involves Lord Asriel (James McAvoy) and Marisa Coulter (Ruth Wilson). In her search for her missing friend, Lyra also uncovers a slew of kidnappings and its link to the mysterious substance called Dust.

Director Otto Bathurst explained that some elements of the book and film had been changed to give the series a more modern feel, compared to the original's Victoriana fantasy.

The series is set to premiere on 3 November 2019 on BBC One in the United Kingdom and 4 November on HBO in the United States and other markets.

When a chance encounter brings soldier John Watson into Sherlock's life, it's apparent the two men couldn't be more different, but Sherlock's intellect coupled with John's pragmatism soon forges an unbreakable alliance as they investigate a series of baffling cases together.

A Royal scandal, a dazzling game of cat and mouse. The seductive Irene Adler is cold, calculating, brilliant. Has Sherlock finally met his match?

Sherlock is back, but will things ever be the same again?