For a musical about a future without death, Deathless feels dissonantly lifeless.

Art that explores the existential malaise of being — particularly works such as this that depict characters lost in their own suffering — unavoidably walk the fine line of succumbing to their own despondency. Depression can make great art, but it can be kind of a bore to watch if the creators unsuccessfully transcend that darkness in some way.

Such is the case with composer and book writer (often a damning combination) Zack Zadek’s tepid and confused new musical at Goodspeed’s Terris Theatre.

Its dramatic lethargy is evident from the start. After newscasts simplistically relay the immortality-for-all backstory — crude exposition is a persistent problem — actress Jennifer Damiano casually launches into the first of many pretty but monotonously bland songs (their blasé shortcomings become more apparent through the unavoidable comparisons to the tidbits of popular songs unnecessarily played throughout, which exemplify how moodiness need not be so muted). Perhaps a sufficiently sizable orchestra and superior amplification system would help, but the number possesses neither the energizing pizzazz nor emotional and psychological resonance to usher the audience into the musical’s world (Damiano’s hollowly subdued performance also does the material no favors). Instead, it — and the rest of the show, for that matter — exists in this sort of off-putting artistic purgatory; consistently pleasant, but rarely engaging.

Which is a shame because the premise bears so much promise (one could even say the show doesn’t…LIVE up to it. Thank you, thank you, Mr. Pun will be here all week). The concept of immortality inherently brings up intriguing questions regarding how finite time influences so many aspects of life. Zadek is at his best when Deathless tackles some of these ideas, such as in “Martin Luther King Jr. Day,” a song that ponders how marriages could possibly work in a world without “until death do us part,” sung by a son (Johnny Shea) who witnessed the dissolution of his parents’ relationship.

If only the musical focused on them.

Instead, that son merely serves as the excessively transparent comedic relief — and a barely funny one at that — to the rote family drama at the heart of Deathless. Unfortunately, the musical never touched my heart, despite the creators’ bald and unconvincing attempts to pull at its strings by awkwardly oscillating between overly familiar, trite melodrama and flatly direct conversations pertaining to the world’s changing existentialism. Zadek seems to have forgotten that classic adage: “show, don’t tell,” which may be why his “Author’s Notes” in the program contains more insights regarding the effects of unlimited temporality than anything found in the actual show.

The characters talk and sing about their troubles, but much like the score, they fail to register on an engaging level. Truthfully excavating their potentially potent emotionality and psychology would require a sense of the tale unfolding in a living and breathing world. But real living and breathing people almost never spend 105 straight minutes telling themselves and each other the story of their internal and external lives, past and present. Instead of showing the audience his characters’ truths, Zadek dully tells them flat-out through his subtext-bereft words, which end up feeling like they stem less from individualized characters and more from a solitary mind.

The cast’s cardboard caricatures compound the thin offerings on the page. Sean Allan Krill is the prototypical sad dad whose vague arc in no way justifies the musical’s final moment. Jessica Phillips barely makes an impression despite the palpable importance of her character (seriously, what was up with her unremarkable first entrance?! Not the best way to introduce a central figure…). And Johnny Shea’s cringingly corny characterization — with an exceedingly on-the-nose costume to boot — dabbles in recycled and reductive stoner tropes (smokers do more than just eat and giggle, people!). Though Zadek saddles Kelli Barrett with a predictably stodgy sister part whose jarringly abrupt appearance midway through the play desperately calls for additional foregrounding, her performance refreshingly injects some much-needed vivacity. Yet from a dramaturgical perspective, her existence basically negates the sole dramatic purpose of Mr. Shea’s character to act as a pro-(immortal)-life foil (and no, providing unfunny comedic relief does not constitute an adequate purpose).

Though Tina Landau’s direction suffers from the staged inertia common to road trip yarns — including falling for the fallacy that distractingly unnecessary projections can compensate for a lack of character movement when they’re stuck in a car for much of the duration  — she thankfully understands how to tell by showing, largely through Dane Laffrey’s set design. By placing the band in the back corner of the stage, she draws a subtle connection between the death-inspired and thus death-centric music and the marginal role that the looming presence of death seems to play in the “back corner” recesses of our daily psyches. Since limited time obviously influences everyone every day, death must affect us unknowingly at all times, in the same way the audience may not always notice the band while surely hearing its music at every juncture.

For the sake of his musical’s future life, Zadek should follow Landau’s “show, don’t tell” lead. If not, it will have trouble finding a hospitable theatrical home, too small for dwarfing-prone big houses and too pedestrianly-imprecise for perceptively-acute intimate spaces.

Without major changes, Deathless may in fact prove short-lived.