David Harbour and Millie Bobby Brown Playing Father and Daughter in New Series

David Harbour and Millie Bobby Brown have no drama ... except for the new one they're filming together ... a Netflix project reuniting them as dad and daughter.

Netflix announced the pair will helm a new series together for the streamer ... with David playing a disgraced FBI agent searching for his daughter, Millie, who vanished on a mission after following him into law enforcement.

Jack Thorne -- creator of the hit TV series "Adolescence" -- is behind the new show, which doesn't appear to have a release date yet.

As you know ... David played Millie's dad on the Netflix hit "Stranger Things" for all five seasons before it ended in December.

Rumors about a fractured relationship between the pair cropped up during the press tour for the final season ... rumors Millie vehemently denied -- going as far as saying she always felt safe with him on set.

David recently said these reports drove him to a mental health crisis ... including an episode where he stole a man's hat at a California bar ... and hinted at a future project with MBB.