It almost seems like a screenwriting dare, to craft a movie with three separate and seemingly unrelated acts using the same three actors and essentially the same central theme in all three, and then mixing them up in hopes of proving a point about something as weighty as the nature of creation. If you’re already confused, join the club. It’s a dare that the writer and director John August seems excited to attempt in “The Nines,” but one that’s unneeded and, all things considered, unwise. In pushing the envelope not once but in three cyclical stories, Mr. August has broken one of the cardinal rules and the taken the audience the long way around.

Not that the script’s asides, parentheticals, hyphens, and semicolons aren’t interesting. To the contrary, there’s juicy stuff to enjoy here — it’s just that, at journey’s end, “The Nines” sinks like a dead weight. About the time characters start speaking in grand metaphors, and things take a turn away from the lighter world of showbiz and toward themes more biblical in nature, the project’s three-pronged structure becomes a liability. We’re suddenly being asked to follow people we don’t know into a grand philosophical debate that we don’t quite understand.

In the first act, dubbed “The Prisoner,” a muscular movie star (Ryan Reynolds) is joined by an overweight publicist (Melissa McCarthy) during his arson-related house arrest, all the while flirting with his beautiful blonde neighbor (Hope Davis). In the second act, called “Reality Television,” a chic screenwriter (Mr. Reynolds) polishes the pilot of a new television show in hopes of convincing a beautiful blonde studio executive (Ms. Davis) that his overweight female lead (Ms. McCarthy) will “play” to urban audiences. In the final act, “Knowing,” a fit-and-trim husband (Mr. Reynolds) and an overweight wife (Ms. McCarthy) find themselves stranded with their daughter (Elle Fanning, who also appears in all three shorts) after a nature hike, and the husband’s attempt to save them is brought to an abrupt end by a beautiful blonde hiker (Ms. Davis) he meets along the way.

“The Nines” is a trippy, cerebral, and occasionally bewildering hodgepodge of stories and themes, and there’s something enticing about the way Mr. August — who wrote the 1998 teen drug caper “Go” and the underrated “Big Fish,” and who started working on this project after what he describes as a creative breakdown — finds ways to interweave these incongruous fables. A cryptic Post-It note that is written in the second act pops up mysteriously in the first act. The footage of the television pilot seen in the second act suddenly becomes the central story in the third.

Toward this end, we take note of themes that repeat in each short film —notably a theme of creative spirits being suffocated by forces beyond their control, and a superficial theme of outer-vs.-inner beauty. In “The Prisoner,” an actor is literally imprisoned in his house, confined by an electronic ankle bracelet, all the while being pursued by the wealthy neighbor who mocks his overweight publicist. In “Reality Television,” the screenwriter finds himself trapped in the absurd world of broadcast television negotiations and finds himself a prisoner to a documentary crew that follows him relentlessly. He’ also subject to the whims of focus groups and studio execs who want him to cast a beautiful superstar instead of his close, overweight friend.

In “Knowing,” a husband and wife are at the mercy of their cell phone networks and dependent on the kindness of strangers.

If taken literally, the climax of “The Nines” is far less interesting than its larger implications. As Mr. August cycles through his various characters and scenarios in rapid-fire fashion, what towers above all else is a sense of empathy — a rejection of the many ways we are pitted against one another on a daily basis.

If for no other reason, “The Nines” is worth seeing for its cast, which does more here than simply don new wigs, clothing, and accessories as they branch out to play multiple characters. Ms. McCarthy and Ms. Davis work the full range of human emotions, playing women who range from seductive to domestic, from the cheerful to the wounded. It’s Mr. Reynolds, though, who delivers a career-altering slate of performances, starting in a more sarcastic place with his actor in “The Prisoner” before assuming a more conflicted role as a backstabbing writer, and a more profound one in “Knowing.” He and his castmates draw us to these characters as they push us forward through a densely packed philosophical puzzle, searching for coherence. That said, it’s a fight we shouldn’t have to wage. It seems Mr. August, who structures his film awkwardly and arbitrarily, preferred the dare, and Mr. Reynolds, Ms. McCarthy, and Ms. Davis sought out the truth.