The plot in TA is very pedestrian and thin, it's downright a commonplace trope. But the characterization in it and the balance of them works out well and it's just a fun movie that doesn't really shortchange any of the characters. It's a good, fun, movie. Not deep or meaningful but just fun..
The plot in TDK is that a psycho with face paint is committing mass murders in a city and a neurotic in a costume stops him. This is actually the same plot as Burton's Batman
. The story is told far differently in each movie, but it is the same story. Burton puts in far more backstory for his psycho, while Nolan leaves it blank. Leaving it blank lets the viewer ponder; it's not genius to leave it blank, it's another trope that's used often, like with Wolverine for decades in comics. TDK works, and is a fine movie, but the plot is just the same plot we've seen a hundred times.