"Manifest" is based around a group of passengers who board a plane, Flight 828, and experience a period of severe turbulence during their trip. When they finally land, they're told that it's been five years since they originally took off, and that everyone on the plane was presumed to be dead. The passengers' sudden and inexplicable reappearance throws everything into question, especially when some of them start to hear voices and visions, which they refer to as "callings."
The fourth season is set to reveal what actually happened on Flight 828, and finally give fans the answers they've been searching for. The new season will be released in two 10-episode parts on Netflix. Per the official description, two years have passed since the murder of Ben's (Josh Dallas) wife Grace (Athena Karkanis). Since then, he's stepped down from his job as the co-captain of the lifeboat to focus on the search for his missing daughter, Olivia (Luna Blaise).
This leaves Michaela (Melissa Roxburgh) to do the job alone. But with the government following all of the passengers, and the death day approaching, the arrival of a mysterious package will upend everyone's lives.