This movie made it to the top of my Netflix queue and finally arrived. The plot of Flightplan hinges around the disappearance of Kyle Pratt's (played by Jodie Foster) daughter during a long haul plane flight. Of course we know her daughter exists and was on the plane, so I watched the movie looking for a believable explanation for what was happened. I was quite pleased to find the explanation was pretty good and tied into the plot very well.
At the start of the movie, Kyle Pratt, a jet engine propulsion engineer, is distraught over the apparent suicide of her husband. She and her daughter Julia are flying the casket home to the United States for burial. During the flight Kyle takes a nap and wakes up to find her daughter Julia missing and that nobody remembers her being on board. She uses her familiarity with airline industry protocols to insist on a search that turns up nothing... meanwhile the Captain shows that the passenger manifest doesn't ever show her daughter boarding the plane. Kyle attempts to convince the air marshall Carson (Peter Sarsgaard) that she isn't delusional while she uses her familiarity with airplanes to take matters into her own hands.
I felt the movie had a definite Hitchcock influence, and I liked it quite a bit. So to spoil the plot, here is the explanation. First, the air marshall is a hijacker who enlisted one of the flight attendants to doctor the manifest and also report that the section she searched was clear. Her husband didn't commit suicide - he was pushed off the building in order for the hijackers to smuggle in explosives in the casket. The hijacker's plan was to establish Kyle as a delusional woman extremely distraught over her husband's death, who flipped out and hijacked a plane, and then blew it up after the other passengers were released. Her background in the airline industry, the death of the husband and the imagined missing child were to be used to blame her and cover up the real crime. Of course, she figured this out and thwarted these plans.