If you’ve heard of Swiss Army Man, it’s likely for one thing and one thing only: this is the movie where Daniel “Harry Potter” Radcliffe plays a farting corpse with an erection. But rather than the childish super-gross-out comedy that short pitch would seem to suggest, Swiss Army Man is actually quite a sweet indie comedy-drama. With some super-gross-out comedy thrown in, natch.

The plot that leads us to the farting boner corpse begins with Hank (Paul Dano) stranded on an island and, in his lonely despair, attempting suicide. Then he spots a body washed up on the nearby beach. It turns out this isn’t a new friend, because he’s dead. Hank dubs him ‘Manny’. One thing leads to another and Hank uses Manny’s gastric expulsions to create a kind of jet ski that propels them off the island. Hank soon discovers the corpse has myriad potential uses (hence the title), especially when he starts to talk…

Swiss Army Man is kind of like Cast Away if Wilson the volleyball was a farting corpse. Hank despairs at his situation, chats to the technically-inanimate Manny about it, and together they begin to work through the human condition. In between using Manny’s rigor mortis-powered limbs to chop wood, or his boner as a magic compass to guide them home, that is. I was going to say “it’s that kind of movie”, but I’m not sure there’s ever been another movie quite like Swiss Army Man.

As well as the indie ruminations on the purpose and meaning of life, there are some mystery plots in play, just to keep things engaging. Who is the woman Hank keeps seeing in flashbacks? How many of Manny’s abilities are real and how much is just in Hank’s head? I mean, Manny can’t really talk… can he? What if Manny’s not the only one who’s dead? Maybe these shouldn’t be given so much focus — I don’t think the film wants to be about such plot mysteries — but they were the kind of things running through my head while watching, because you know there’s bound to be some kind of twist or reveal for what’s actually happening. Naturally, I won’t spoil that here; but perhaps the film plays even better on repeat viewings, when you can set aside such wonderings and focus even more fully on the friendship between man and corpse.

That’s naturally powered by the two lead performances. Dano is very good as a man who’s feeling suicidal for, as it turns out, more reasons than “I’m alone on an island”; though enacting such patheticness (as a human trait rather than a criticism of his mental condition) seems very much within Dano’s wheelhouse. Radcliffe, however, is simply brilliant. Manny comes back to ‘life’ as a kind of innocent, unsure of how the world works and driven by his basest feelings; a reflection of all our inner psyches, in a way. Physically constrained by being, y’know, dead, Radcliffe manages to convey so much despite — or perhaps even partly because of — the limitations imposed upon him.

Made for a relative pittance, technical merits are also strong, with neat special effects to convey Manny’s abilities, and a very indie-ish but fitting vocal-driven score by Andy Hull and Robert McDowell. Interestingly, the Blu-ray contains an option to watch the film without the score, which (based on the few bits I sampled) creates a remarkably different experience. That’s true of most films, of course, but here it dramatically changes the mood of some scenes. It’s less magical, in a way, and sadder, and maybe creepier, which is not the point or message of the film.

“The farting boner corpse movie” is the kind of pithy description that will put many viewers off, but hiding behind the gross-out facade is a sweet comedy-drama about human interaction that, in its own way, is an incredibly moving, perhaps even heartwarming experience.

Swiss Army Man is released on DVD and Blu-ray in the UK today.