And yet when Vader catches up and boards her ship at the beginning of Star Wars, Leia tries to pretend that she's on a "diplomatic mission." Again, Vader literally just watched her fly here from a fucking space battle. That's like taking a dump in the middle of a police station, then slowly walking backward out the front door without ever breaking eye contact with the chief of police. Leia may look ridiculous trying to pull that off, but Vader arguably looks even sillier for getting all flustered and even bothering to argue with her sad excuse of an excuse. It's almost like a deleted scene from Spaceballs.
At that point, Leia should have just claimed a womp rat ate the plans, or that she flushed them down the toilet. Anything is better than "Oh no, you must be looking for some other princess who recently came from that off-limits planet where a major theft occurred."