Mary Poppins Returns has rounded out the brother/sister duo seen in the original Mary Poppins.

Emily Mortimer will play Jane Banks, one of the children Mary Poppins nannied in the 1964 musical starring Julie Andrews. The other child, Michael Banks, will be played by Ben Whishaw.

Emily Blunt is set to star as Mary Poppins, and Meryl Streep will play a character named Topsy.

From Disney: “Blunt has been cast as Mary Poppins and Miranda will play a new character, a street lamplighter named Jack. Drawing from the wealth of material in P.L. Travers’ seven additional novels, the story will take place in Depression-era London (when the books were originally written) and follows a now-grown Jane and Michael Banks, who, along with Michael’s three children, are visited by the enigmatic Mary Poppins following a personal loss.

“Through her unique magical skills, and with the aid of her friend Jack, she helps the family rediscover the joy and wonder missing in their lives.”

Mary Poppins Returns, which co-stars Lin-Manuel Miranda, hits theaters December 25, 2018. Like the Christmas 2014 release of Into the Woods, Disney is aiming to make it a holiday hit.

Mortimer is perhaps best known to our readers for her starring role in HBO’s The Newsroom.