The story follows a young misfit girl named Barbara who grapples with monsters both real and imagined in her life, reported Deadline.
The 37-year-old "Guardians of the Galaxy" star will play Mrs Molle, the school psychologist who helps Barbara through her struggles and forms a tight bond with her as a result.
Saldana joins Madison Wolfe as Barbara, who was chosen for the role after a nationwide search of over 500 actresses.
Saldana was recently seen in "Infinitely Polar Bear" opposite Mark Ruffalo, and will soon be seen in the upcoming "Star Trek Beyond".