It's hard to buy the nonchalance of the homosexual experimentation that takes place between two teenage best friends in this Spanish coming-of-age fable "Nico and Dani," which takes place over a few weeks of summer in a seaside town near Barcelona.

The problem has nothing to do with the performances of Jordi Vilches and Fernando Ramallo, the two brilliantly ingenuous young actors in the title roles. It has nothing to do with the circumstances of the initiation of their libidos -- they're 15-year-old boys with time on their hands and partners (initially girls) at their disposal.

But when they start...errr...manually pleasuring each other, completely out of the blue, the viewer gets mentally yanked right out of the story by involuntary attempts to figure out what signals were missed that indicated these kids were so free with each other. I don't know about you, but nobody I knew -- gay or straight -- did this sort of thing with their pals when I was 15.

Nico and Dani aren't lovers. They're school chums. In fact, Dani's the only one who is beginning to realize he's gay. Nico has just come to visit Dani so he can hone his skirt-chasing skills on the bikini-clad local girls, like flirty Elana (Mariete Orozco) and virginal Berta (Esther Nubiola) -- two sweet beauties who take a shine to our heroes.

When the film hasn't gone off on an awkward sexual tangent, the gawky credibility of the actors' teenage tenuousness really sells the story of these boys. It's packed with 100-percent authentic moments of adolescence, like the party scene in which Nico and Dani end up feeling two feet tall when they arrive to see their girls talking to a pair of older, much taller, more manly boys. Later in the same scene they pair off boy-girl, boy-girl for an ungainly slow-dance that will induce flashbacks in anyone who ever rocked clumsily back and forth with their hands on someone's hips in a school gymnasium.

In such moments "Nico and Dani" is superbly spot-on. Later, when Dani is charmed by an older man and begins to embrace his sexual preferences, the film moves into an honest portrayal of homosexual and heterosexual awakening. Writer-director Cesc Gay (who loosely adapted the film from a stage play called "Krampack" -- slang for the boys' sexual games) clearly remembers well what it is to be at that age when hormones are raging and confusion is copious.

As a director Gay also clearly understands his medium, taking proficient advantage of the film's Mediterranean small-town atmosphere and giving "Nico and Dani" a contagious lightness of spirit.

But every time Gay jumps headlong into one of these tactless sexual scenarios between the boys, the picture derails because these scenes seem so very out of character.

Had there been some establishing of Dani's sexual leanings, or even one moment in which Nico was taken aback by his friend's queer (in both senses of the word) suggestions -- thus providing a base from which to build this angle of the story -- "Nico and Dani" might not feel so bumpy and uneven, allowing its more admirable elements to come through.