First released in 2005 for the Nintendo Gamecube, the 4th numbered entry in the Resident Evil series sees protagonist Leon Kennedy on an assignment to rescue the U.S President's missing daughter Ashley Graham in an area of Europe. He comes across a village where the citizens are acting strongly and all out to murder him, as well as mutated monsters.
This entry changed the gameplay formula seen in previous games by having the camera always focusing behind Leon in a third-person, over-the-shoulder perspective and focused more on action, whilst keeping the scares. Critically acclaimed with a 96/100 on Metacritic and receiving many awards, Resident Evil 4 is regarded as one of the greatest games of all time.
Earlier in the plot, Leon encounters the main villain Osmund Saddler, who reveals that he has infected him and Ashley Graham with a parasitic creature called "Las Plagas." It is growing inside them and once they are fully hatched, Saddler will have complete control over them, making them his puppets. In the last cutscene of Chapter 5-2, Leon and Ashley run into Saddler where he uses his powers over "Las Plagas" to stop Leon in his tracks whilst he takes control over Ashley. Fully under his control, Ashley is commanded to go off with Saddler. Leon places a tracking signal on her back so he can try and catch up.