Doctor Foster tells a trusted GP who is the heart of the town and a woman people can trust. However, Doctor Gemma Foster's life is about to explode when she suspects her husband is having an affair which sets her on a mission to find out the truth. Doctor Foster throws herself into an investigation that is going to propel her, her family and even some of her patients, into chaos. Piece by piece, Doctor Foster uncovers secrets that shock her to the core. Now she has to choose how to react. One thing is certain, she is going to behave in ways she could never have imagined.