In Billy Wilder’s Sunset Boulevard, Joe McGillis (William Holden) tries to knock some sense into fallen film star Norma Desmond (Gloria Swanson) by sarcastically informing her, “There’s nothing tragic about being 50. Not unless you’re trying to be 25.”

It appears that the characters in writer-director Paul Cox’s “Innocence” aren’t following Joe’s advice. They’re both around 70 years old, but that doesn’t stop them from having a love affair as vital as their first one, 50 years ago. The film wholeheartedly believes in the power of first loves, even the second time around.

Cox makes no apologies for the age of his characters. In fact, he celebrates their love and wisdom in the face of death and expectations. While he succumbs to melodramatic techniques and slow-paced sentimentality, the message transcends the mushy medium.

Hollywood usually isn’t friendly to anyone over 25, as Norma Desmond knew too well. So when “Innocence” opens with young lovers, it seems that the film will continue along this path, throwing in the standard jilted admirers and disapproving parents. But instead, with flowing water and the papery voiceover of Andreas (Charles “Bud” Tingwell), we travel forward 50 years and arrive in the present, when Andreas asks his first love Claire (a youthful Julia Blake) to dinner.

The reunion sparks a cautious love affair, to the disbelief and outrage of Claire’s husband of 45 years, John (Terry Norris). They make love, share picnics, and relive old times despite the constant, lurking presence of death that hovers around them in the form of cemeteries, funerals, and skulls.

Death soon invades their lives: Claire has a heart condition and Andreas has cancer. Nonetheless, the couple has more life than the young people that populate the screen’s edges. That a film would focus on the elderly is itself a daring move, but that the film would also treat them like whole people is nearly unbelievable.

“Innocence” benefits from this wise choice, allowing the characters to experience a wide range of emotions. At times they act like children — Claire throws a particularly immature fit early in the affair — but generally they are conscious of their age without succumbing to it. Both actors are comfortably unglamorous and mature. Their performances are tempered and suited to the portrayal of experienced characters.

Cox resists the urge to make the lovers relive their pasts — he places them securely in the present. Claire and Andreas’ confidence in their age is reinforced by the camera. Cinematographer Tony Clark dismantles the traditional flashback, favoring a rapid but natural progression of snapshots from the past. At some overly nostalgic moments the shots seem like home videos a la “The Wonder Years,” or like flickering old movie reels.

Clark uses trains, reflective surfaces, and trees to switch quickly to the past just as a particular sensation might trigger a memory. Eventually he integrates past and present: mirrors first reflect youth, then with a pan or a bit of fog the image transforms to one of old age. The lovers turn their heads and find each other transform, instantly, from their present to past selves, and vice versa.

It is when these juxtapositions of life stages confront death that “Innocence” simultaneously shines and suffers. While death hangs over the film from the onset, it collides with Andreas when he visits the cemetery, where several workers — modern day Shakespearean gravediggers — are moving the grave of his long-deceased wife. The workers exchange jovial remarks about the value of cemetery real estate as they pick up dirty bones and a brown, caked skull. Andreas, in an eerie echo of the previous past-and-present unions, imagines the naked, bruised body of his young wife in the coffin.

These dreamlike sequences (including one actual and very disturbing dream sequence in a hospital) bring death a bit closer to home, but love prevails, of course. And with love comes melodrama: the arguments between Claire and John are particularly overdone. Some moments of joy are also over the top, especially when Claire dances to an obscenely cheerful accordion.

Nonetheless, the melodrama seems to have a clear purpose, and that is to demonstrate Claire and Andreas’ brazen defiance of death and of expectations. If only Hollywood could accommodate more characters like these. Unfortunately, the elderly are generally left to be grandparents, crotchety neighbors, or villains. They are never as whole as they are in “Innocence.” Here, they drink, they curse, they find surges of life in strands of music. Any tendency towards melodrama — some pieces of the score, whole chunks of dialogue — are eclipsed by the deep desire we feel for love’s conquest of age.

But, despite these brief moments of transcendence, old age is old age. As death circles closer, so does Clark’s camera. Death is barely stifled by curtains and veils; it is debated and pondered. Cox’s dialogue trudges heavily, but it is difficult to dislike a film that isn’t afraid of taking the cinematic oomph out of life’s biggest elements — love and death — and making them commonplace and intelligent.

“Innocence” treads cautiously between fleeting life and slow death. The film’s melodrama is its liveliest element, but the pace is otherwise sluggish. While this may seem like a fault, herein lies the film’s strength. It is proud of its romantic message and confident in its rhythm — the rhythm of life’s end, with its oddities, uncertainties, and moments of pure vigor.