A man's stress manifests itself in the form of a vicious, spiteful butt-demon (yep, really) in the horror comedy 'Milo,' and although it's packed with a fantastic cast, it doesn't quite stick the landing.

Ken (Ken Marino) is an accountant who works in a high-stress environment and whose wife is anxious to have a baby, but his own father issues are holding him back from procreating. All of that stress compounds and manifests in the form of what his doctor believes to be a benign polyp, but it's not -- nope, the thing lurking in Ken's intestinal tract is a demon, and it's out to kill everyone who wrongs its host.

'Milo' is surprisingly heartfelt and thoughtful, using its titular butt-demon to help teach Ken a lesson about fatherhood and reconciling with his own anger. Milo is the physical representation of everything Ken is afraid of and everything that could ruin his happiness -- when we don't recognize, accept, and try to make peace with our own flaws, those flaws can hurt the people we care about the most. It's a simple metaphor, but one that sets 'Milo' apart from other comedic horror fare. Unfortunately, the tone of the film isn't quite consistent, and the comedy not quite biting enough to sustain a 90 minute narrative.

At its best, 'Milo' is an homage to '80s creature features, updated with the sort of wacky humor we've come to expect from graduates of 'The State' like Marino. He's joined by a great cast, including Gillian Jacobs, Patrick Warburton, Steve Zissis, Peter Stormare, Stephen Root, Mary Kay Place, and an outstanding Kumail Nanjiani -- the latter of which is on the verge of breaking out in a big way, with recent roles in 'Newsreaders' and 'Portlandia.' Jacobs is the weak link, as her character does little more than look shocked and confused, while Stormare is a close second, miscast as a new-age therapist with an annoying pet parrot.

The creature design calls to mind films like 'Xtro,' 'Basket Case' and similar '80s horror fare, though Milo has an adorableness to him in the vein of  -- who knew something from your colon could look so damn cute? Milo looks like one of the creatures from 'The Gate' mated with Gizmo from 'Gremlins' and had an adorably vicious butt-baby. The use of practical effects is a welcome respite from big budget studio filmmaking, which relies heavily on CG for blood and gore, but 'Milo' does it right by using practical effects as a primary visual tool and very minimal CG only to enhance a couple of the film's bloodier moments.

At times, it seems as though director Jacob Vaughan (who co-wrote the script with Benjamin Hayes) has made a film that feels tonally similar to a Troma movie, which isn't a great thing. Vaughan has worked as an assistant editor on two features from brothers Jay and Mark Duplass, and the pair lend their names to 'Milo' as producers, though this film has little in common with the sort of fare we've come to expect from the brothers Duplass. 'Milo' can rely a little too heavily on the brown jokes to the point where it feels a bit one-note, with occasional moments of subversive humor.

Once you grasp onto the film's fairly straightforward metaphors, 'Milo' has little else to say and starts running in place -- the ensuing redundancy makes the story seem better suited for a short film than a feature. Fear and sense of humor are two incredibly subjective things, so when you combine the two to make a comedic horror film, the tone can be tricky to pin down. 'Milo' succeeds about half the time, but Vaughan traps himself in a corner by building a film inside one big butt-joke, and unlike his antagonist, he's never really able to escape it.

Rating Meter 6

'Milo' premiered at the 2013 SXSW Film Festival.