If you just watched the opening half hour of My Cousin Vinny, I’d definitely excuse you for thinking that it’s a merely average comedy. The set-up of the film is nothing special: A series of misunderstanding and farcical twists of fate leave two New Yorkers on trial for a murder they didn’t commit in Alabama. The hapless Vincent Gambini (Joe Pesci), a cousin of one of the defendants, agrees to defend them. Vinny brings his bickering fiancee, Mona Lisa Vito (Marisa Tomei in a performance that won a controversial Academy Award) to Alabama.

It could have played out sloppily, with insulting jokes about southern life and overly broad caricatures of snotty New Yorkers.

But then something interesting happens. The overconfident lawyer Vinny is lying in bed with his fiancee, and she asks him what’s wrong. He can’t sleep — he’s worried he’s going to let down his cousin, who’ll spend his life in jail. Vito argues that he SHOULD be worried, that this isn’t a game, that something would be wrong if he wasn’t.

All of the sudden, Vinny and his fiancee have some depth and shading. It’s a turning point for the movie, which not only fleshes out its characters from that point (adding some legitimate drama and tension to the story), but the jokes become funnier and less wacky.

The second and third acts of My Cousin Vinny are truly great, in my opinion, often hysterical and always well-written. The courtroom scenes in particular are mesmerizing as Vinny’s distinct swagger clashes with the good-old-boy southern charm of everyone else in the trial.

It’s also a legitimate courtroom drama, slowly unfolding and twisting in unexpected ways. It’s not clear until the last few minutes of the trial what the lynchpin of the evidence is going to be — or if there’s even going to be one.

It’s also, in broad strokes, a fairly realistic depiction of a courtroom: There are no evil attorneys or conspiracies, just a bunch of people trying to do their job. Nothing overtly wacky. Pesci is believable as a clever but inexperienced lawyer stuck in a culture clash.

The cast is solid all the way through, but there are three obvious standouts. (The Karate Kid as defendant Bill Gambini is fine, but not particularly noteworthy. I always forget who plays him until I look the movie up on IMDb.)

First is Fred Gwynne as Judge Haller in his last movie before dying of pancreatic cancer. Gwynne (most famous as the Frankenstein’s monster-esque Herman Munster from The Munsters) serves as an antagonist of sorts, but he’s there mostly to trade barbs with Pesci. I was actually shocked to learn that New York-native Gwynne doesn’t have a southern accent; his drawl is extremely convincing.

Second is Tomei. Tomei’s Best Supporting Actress Oscar win from this movie has been dubbed the biggest upset in Academy Award history — or, by less generous writers, the least-deserving. I don’t really know how her performance compares to the other nominees from that year, but she’s absolutely outstanding here. She improbably shines as Pesci’s equal, never letting him overpower the scenes they share. In many ways, I think she had the hardest job of any of the actor — her character is written as kind of snotty — but she manages to make Vito a convincing and enjoyable character.

But the show-stealer is Pesci, who absolutely thrives as Vinny Gambini. He is riotously funny, but he plays the Gambini with seriousness and intensity. It prevents the character from becoming too broad or silly, and it also makes the jokes all the funnier. Pesci frustrated because his car is stuck in the mud? Funny. Pesci in the same scenario, but channeling his famous psychotic fury? Unforgettably hilarious.

I also can’t help but think of this as Pesci’s signature role. I know, that’s sacrilege. But every time I see one of his movies, even Goodfellas, I think to myself something like “why is Vincent Gambini breaking into Macauly Culkin’s house?”

In short, My Cousin Vinny is a delightful courtroom comedy with a fantastic cast, brilliant script, and even a strong story. If nothing else, I’ll never look at the word “youths” the same way.