Even though Kong: Skull Island wants movie audiences to root for the titular giant chest-pounding gorilla, the new monster flick has a human soul. John C. Reilly’s performance as marooned WWII veteran Hank Marlow is convincing, heartfelt and hilarious. And without him in the movie, all this monkey business would be a good bit harder to stomach.

Mild spoilers for Kong: Skull Island ahead.

Kong: Skull Island boasts a dizzying number of big-name Hollywood stars, making it feel like the August: Osage County of sci-fi monster movies. Even though John Goodman, Tom Hiddleston, Brie Larson, and Samuel L. Jackson are in this movie, you’ll hardly remember they were there — and that’s because they’re all eclipsed by John C. Reilly’s charming performance.

To be fair, no one gives a particularly bad performance, but the stakes for the characters sometimes ring a bit generic. Samuel L. Jackson goes full-on Captain Ahab against the White Whale of Kong. Brie Larson is a strong photographer with little to do other than run. Tom Hiddleston looks like he’s going to the gym a lot as he expertly cleaves a bunch of pterodactyls with a sword. Younger actors Corey Hawkins and Tia Jing are charming enough but given nothing cool to do until the post-credit sequence.

But none of these characters truly get you to care about them until the Skull Island gang chances upon John C. Reilly’s Marlow, a person who acts like he’s in a real movie rather than a hazy homage to a bunch of other movies.

Marlow wields the weapon of his former enemy, a Japanese pilot named Ikari

This isn’t to say Marlow is some kind of brilliantly original concept. He’s a stock character, too: a weird old guy who is both batshit insane and heroic at the same time. And yet, Reilly gives the character so much heart, even the most cynical moviegoer will suddenly be onboard with the rest of the film. Because Kong: Skull Island seems to take itself a little too seriously at times, it’s also in search of some kind of real emotional stakes to justify that seriousness. And once Marlow is introduced, all of those real stakes are established quickly and easily.

But the deftness of the character is that the entire movie is framed as actually Marlow’s story. The very first scenes show a young WWII pilot crash-landing on a mysterious island somewhere in the Pacific Ocean. A Japanese pilot named Gunpei Ikari (Miyavi) has also crash-landed, and just as the two are about to battle to the death, Kong bursts in and the titles of the movie begin. The cool thing about this is that the audience forgets about this little prologue right up until the moment that Marlow is reintroduced, now as the grizzled old Reilly.

Because Kong: Skull Island takes place in 1973, Marlow has been hanging out on the island for three decades. He doesn’t understand why people like David Bowie, cracks jokes about everyone likely dying at any second, and genuinely longs to be reunited with his family. He also reveals he and his former Japanese enemy Ikari formed a friendship, which makes us like him even more. When he admits he just “made up” the name for the murderous lizards, the Skullcrawlers, it’s hilarious, but it’s endearing too.

While most of the human characters in Skull Island feel like fodder for Kong or the Skull Crawlers to murder, once Marlow appears you really hope he survives. And in a movie like this, he totally could have been killed off. The other grizzled veteran character — Samuel L. Jackson’s Col. Packard — dies fighting a hopeless war, as do many of the men under his command. The script could have easily hewed predictable and found Marlow sacrificing himself to save the younger characters, a war hero to the last.

But the movie didn’t go there. Instead, Marlow survives the entire ordeal and even is reunited touchingly with his wife and son in the film’s coda. Actor Will Brittain does sly double-duty as both young Marlow at the start of the film and Marlow’s son at the end. It’s the kind of thing that’s barely noticeable, but reveals a thoughtful character arc nonetheless.

Amid all the Skullcrawler jaws being snapped open by King Kong, and the results of Tom Hiddleston’s gym membership, John C. Reilly’s turn as crazy Marlow stands out. By cackling like a madman, he saves everything in this monster mash from feeling too disposable. Which, in the end, is pretty heroic.