Viewers who adore the British period drama "Call the Midwife" will end the year on a high note as the show's Christmas special is set to air in a few days. And to cap off the year, the series has already been picked up for a sixth season.

The show has always aired a "Call the Midwife" Christmas special ever since its inception and the tradition continues this year. A synopsis posted on BBC hints at the people of Poplar excitedly getting ready for Christmas. Despite her loss, a grieving mother feels the magic of Christmas, thanks to an unexpected surprise. Meanwhile, one of Nonnatus House's own might be in trouble as Sister Monica Joan goes missing.

The trailer for the Christmas episode does reflect the Christmas cheer, but it also gives viewers glimpses of sadness. The clip starts with a simple street scene of people getting ready for the holidays and the women of Nonnatus dealing with the demands of their work and the upcoming festivities. There are some happy scenes with Santa, the boy scouts singing a song and a baby being born, too. This is interspersed with scenes of loneliness, as a man walks away from the sea and a woman slowly trudges along a path. The clip ends with the nuns and midwives of the Nonnatus House standing in front of churchgoers, getting ready to sing.

The series is based on the memoirs of Jennifer Worth, a former nurse, who worked in the Poplar district of London. The drama's first season quickly drew positive reviews and set the stage for more episodes. "Call the Midwife" has reportedly already been renewed for a sixth season even before the release of the fifth season.

In a statement, "Call the Midwife" showrunner Pippa Harris said she was delighted that BBC had already commissioned a sixth season even before season 5 went on air. Harris also mentioned that the success of the show was due to "the incredible writing skills of Heidi Thomas and the talent and dedication of our wonderful cast and crew."

The "Call the Midwife" Christmas special will be aired on Dec. 25 on BBC1. Season 5 is slated to be released in the U.S. on April 3, 2016 on PBS.