Two of the finest, most idiosyncratic actors working today are gloriously paired in Italian director Luca Guadagnino’s “A Bigger Splash.” Tilda Swinton and Ralph Fiennes ignite this languid story of love, regret and rock music as former lovers and close friends whose long-term intimacy flutters between platonic and sexual, all the while observed by her younger boyfriend and his much younger daughter.

Swinton is an “always watch” actress; if she is in a movie, you should at least check it out. Her starring turn in this director’s 2009 movie “I Am Love” induced widespread swooning over a visual style that is also gloriously displayed here. As rock star Marianne Lane (Swinton) recovers from throat surgery that leaves her unable to speak, she is lovingly and almost silently served by her hunky younger boyfriend (Matthias Schoenaerts). Into their clothing-optional reverie on a sun-drenched Italian island explodes their mutual longtime friend Harry (Ralph Fiennes), who is simultaneously, brilliantly delightful, annoying, needy and attentive.

What follows is a gorgeously photographed, incredibly stylish character study, as Swinton and Fiennes literally and figuratively dance around their feelings, past and present. And speaking of dancing, Fiennes delivers a career high in a sprightly dance sequence to a Rolling Stones album he plays, trying to impress his daughter and everyone else with his many famous associations as a record producer. Harry seems always to be trying too hard, yet he is undeniably successful and talented. Fiennes gives him incredible dimensions.

Things come to a head in the film’s shocking final scenes, but the excellent dialogue and great performances were enough for me up until that point. Apparently Tilda Swinton made the suggestion to cut all her character’s dialogue and make her mute from surgery, and her attempts to stop herself from screaming at the end are amazing. Swinton is one talented alien goddess. She’s incredibly specific physically, yet a chameleon as an actress.

Even the basically vapid Dakota Johnson brings something to her role as Fiennes’ recently identified daughter; she is yet another puzzle piece from the characters’ storied pasts. Flashbacks fill in some of the details, as does perfectly rendered dialogue between characters who know everything about each other, but still find ways to explain themselves to the audience.

As for the plot of “A Bigger Splash,” nothing much happens. Yet the experience of watching it is dynamic and exciting, even suspenseful, and not just to see what Swinton will wear next. Her relationship with Schoenaerts is as subtle and quiet; hidden depths are suggested in the care they show for each other.

His suicide attempt and subsequent sobriety are hot-button topics. We only find out in a flashback that it was Harry who introduced him to Marianne in the first place, essentially handing her off with his blessing.

This film is basically two hours of sexual tension, fabulous caftans, stunning scenery, an awesome soundtrack and nudity. It is also much more than that, a simmering visual experience that never lets the characters or the viewer relax into the paradise so vividly shown on screen.

“A Bigger Splash” is currently available to rent.