National Treasure” scribe Jack Thorne is penning “Best Interests” for the BBC, a drama series about a family’s fight to save their sick young daughter after doctors say the child should be allowed to die. The four-part series is the first commission for Chapter One Pictures, the U.K.-based producer set up by Anonymous Content, Casarotto Ramsay, and United Agents.

“As a parent of a three year old I’ve looked at the cases in the media about ‘best interests’ with some fascination and a little dread,” said Thorne, whose TV credits include “His Dark Materials” and “The Virtues.” He added: “We are going to try and tell a nuanced story that talks about this issue from all sides.”

Filming commences in 2020. Piers Wenger, controller of drama for U.K. pubcaster the BBC, commissioned the series. “This heartbreaking story delves deep into the inner turmoil these two parents experience when faced with their worst nightmare,” he said. “Jack Thorne’s talent for tackling the most complex and challenging real life stories with consideration, wisdom and vision will make this a series to remember.”

Executive producers are Sophie Gardiner (“Chimerica”), Toby Bentley (“Kiri”) for Chapter One Pictures, Jack Thorne for One Shoe Films, and Lucy Richer for BBC One. The series will be produced by Abi Bach (“The Honourable Woman”).