In the aftermath of his wife's tragic death, David Callaway is faced with the daunting task of rebuilding his shattered life while caring for his young daughter, Emily. As he navigates the murky waters of grief and single parenthood, David is taken aback to find out about Emily's make-believe friend, 'Charlie'. Initially charmed by the whimsical nature of Emily's imaginary companion, David soon begins to notice a disturbing shift in 'Charlie's' behavior, as the once harmless playmate starts to exhibit malevolent tendencies. With each passing day, Emily's mental health declines further, and David finds himself grappling with the terrifying realization that 'Charlie' may be more than just a product of his daughter's imagination - he may be an ominous presence intent on wreaking havoc in their lives.