The 56-year-old actress will lead the cast of the romantic adventure, which Adam and Aaron Nee have signed up to direct.
The project is being envisioned as a reunion for Sandra and Ryan Reynolds, who worked together in the 2009 rom-com 'The Proposal', although the 'Deadpool' star is only loosely attached to the film for the time being.
It is suggested the movie will be a screwball adventure featuring mismatched leads, witty repartee and romance.
Sandra will play a romance author, who discovers that a supposedly fictional city that she had written about is actually real. She and the actor who plays the lead character in her book take a life-threatening journey to find this lost city.
'The Lost City of D' is seen as a major priority for developers Paramount and new motion picture group president Emma Watts.
Dana Fox has written the latest draft of the script which is based on an idea by Seth Gordon, whose previous credits include 'Horrible Bosses'. He will also produce the flick via his Exhibit A banner while Sandra is producing through her company Fortis Films.
The Nees have helmed music videos and are also set to direct the big-budget 'He-Man and the Masters of the Universe' for Netflix.
It will mark Sandra's first project since starring in both 'Ocean's 8' and 'Bird Box' in 2018 – the latter of which became a massive hit for the streaming giant.