A scientist named Dr. Nekhorvich (Serbedzija), who is a friend of IMF agent Ethan Hunt (Cruise), who is in Australia, wants him to escort him to Atlanta, which he does. While on the plane something bizarre happens and Ethan kills the scientist. It is then revealed that Ethan is not Ethan but Sean Ambrose (Scott) posing as him. He and his cohorts jump out of the plane and then proceed to crash it into a mountain. The real Ethan is then summoned by his superior for a mission but before undertaking it he is instructed to recruit a woman named Nyah Hall (Newton), who is a thief to help them. He does and goes to meet his boss who tells him about his friend and the crash. He then tells him since Ethan was unavailable he sent another agent Sean Ambrose who like Ethan is a disguise expert. They then conclude that Ambrose was the one who crashed the plane and took what his friend was carrying, which he called Chimera. Ethan's mission is to get it back. He is then told that Nyah is Sean's old girlfriend and that he wants her back. Ethan is hesitant because it seems that the two of them have connected but is convinced that she is their best chance to find Ambrose, so he asks her and she agrees.
Continuity mistake: The tyres on the crotch rocket motorcycles they were riding kept changing from knobbly tyres to road slicks, back and forth depending on what terrain they were on. Easiest to see when Ethan skids on the road to avoid the white van - clear shot of slick tyres - then about 30 seconds later they're on the dirt, he skids into the old car and you can easily see that he's got off-road tyres front and back.