Blake Lively is forever 29 in The Age of Adaline, and darned if the screenwriters don’t act even younger throughout this logic-stretching romance.

The new film casts the glamorous Gossip Girl alum as a woman cursed to live as a gorgeous twentysomething with both perfect skin and an impressive noggin (i.e., brain). That concept opens the door for plenty of thoughtful scenarios. What are the different ways she hides the fact that she never ages a day? Does having decades of wisdom change the way she interacts with the world? Could she reveal something profound to humanity, something very special she has gleaned from her curious situation?

Not really. Her wisdom more or less ends with crushing it at Trivial Pursuit and putting a forger politely in his place.

And yet Adaline does offer some modest rewards. Lively is a better actress than most soap-style dramas like Gossip Girl produce. And the film gets a firm, insistent pulse when Harrison Ford arrives on screen.

How often could that be said in recent years?

Lively stars as Adaline, who calls herself Jenny as the story opens. A comforting narrator (Hugh Ross) fills in some of the peculiar story gaps. A freak accident left Adaline with a rare condition—she’s trapped at the age of 29 and will never age. Never mind the science behind the incident; Adaline embraces artfully constructed devices over realism. Director Lee Toland Krieger (whose 2009 drama The Vicious Kind remains woefully neglected) handles the tone problems with aplomb.

You simply have to … believe.

What Krieger can’t do is make Lively the kind of performer this often-thin story demands. That’s not to say she’s underwhelming. Her Adaline is confused but confident, a compelling figure worthy of her multiple suitors.

Too often, however, the film puts Adaline in another stunning dress or era-appropriate makeup, reinforcing the actress’s natural beauty while downplaying any observations of Adaline’s inner self. It’s an unforced storytelling error, if a possibly understandable one.

What Lively’s Adaline misses is that movie star magic, the sense that this woman is truly special beyond her genetic hiccup. Why else would we watch as she suffers one style of heartbreak after another? The screenplay doesn’t help matters. We learn early on that she picks up clues that escape most people, but that knack is more or less ignored later on.

And yes, living decades beyond her natural lifespan means that she’s absorbed countless bits of data. That makes her a whiz at board games, but is that really all her unique life has taught her?

Lively gets solid acting support in her first substantial big-screen role. Ellen Burstyn plays her daughter, an old woman who somehow continues to relate to Adaline as a child might. It’s an oddly touching relationship, one that could have been explored in greater detail without harming the main love story.

That story, sadly, is too pat to command much interest. Handsome, successful Ellis (Game of Thrones’ Michiel Huisman) looks like he strolled right out of a Harlequin romance novel. He’s got a perfectly trimmed beard, endless wealth, a gentle sense of humor, and, well, the list could go on as long as the movie’s credits.

Ellis’ attempts to break through the social wall Adaline constructs for herself are both tender and wearying to the audience. Only with Ford’s arrival, playing a man with a curious connection to one of Adaline’s past “lives,” does the film find a sense of purpose.

Ford’s career appears to have bounced back following a particularly ugly run. For years he clung to leading man roles even if the material was far beneath him (see Firewall for a perfect example). Now the seventy-plus star is choosing smaller, more intimate parts, and he’s revealing himself to be a far more nuanced performer than we’d come to expect.

And kudos to the casting agent who found Anthony Ingruber to play Ford’s young self. The Disney “Star Wars” team might want to text the young actor about portraying Han Solo at some point.

Adaline’s final reel features even more hard-to-swallow metaphysics, but by now you’re either lunging for the Kleenex box or rolling your eyes anew. It’s that kind of movie, a wholly sentimental affair seemingly meant to divide audiences into warring factions.

The Age of Adaline offers a magical tweak to modern film romances, earning an A for effort and a B-plus for avoiding the genre’s most overt pitfalls. It emerges as a suitable love story for those who crave even the genre’s lesser tales, but its near-boundless potential remains woefully untapped.