One vacation they’ll always remember

The German film “Summer ‘04” opens with the simplicity of its title: a teenage boy and girl return after a day spent bicycling near the boy’s vacation house close to the Baltic Sea. The sun is shining, but innocence is waning. No one knows it, but nothing will ever be quite this bucolic again.

Starring the luminous Martina Gedeck of “The Lives of Others,” written by Daniel Nocke and directed by Stefan Krohmer, “Summer ‘04” is straight ahead in form but unnerving and unexpected in content.

It’s an unusual drama, one grounded in the difficulty inherent in intimate relationships, in attempting to read and assess the behavior of others. The unpredictability of its plot demands considerable suspension of disbelief, but if you stick it out to the unforeseen conclusion, the rewards are there. Sticking with this film is not difficult because “Summer ‘04” is grounded in the lives and psyches of its five-person ensemble.

Gedeck, who played the compromised actress in “The Lives of Others,” here becomes Miriam, an assured mother to 15-year-old Nils (Lucas Kotaranin) and vibrant companion to Nils’ alpha male father Andre (Peter Davor). Nils has invited his girlfriend Livia (a potent Svea Lohde) to join him in the family’s summer house. Not yet 13, Livia is remarkably precocious, with a charm and charisma that is undeniable, even though Nils would often rather watch documentaries on World War I than hang out with her.

One day, after an afternoon of sailing, Livia comes home not with Nils but with Bill (Robert Seeliger), a considerably older man in his 30s who drives her to the house in a fancy sports car. Bill is handsome and unexpectedly charming, a trait he ascribes to years spent in America. “Have a little patience with me,” he pleads after Andre makes short shrift of his cheerful friendliness.

Andre may have little patience with Bill, but he is indifferent to the man’s hanging out with Livia, as is Nils. Miriam, however, is suspicious of the relationship. But as she confronts him about it, she discovers that Bill’s intriguing back story makes him both a more unusual character than she anticipated and someone whom she is unexpectedly attracted to.

There is really no anticipating the way “Summer ‘04’s” complex relationships will play out. Director Krohmer creates a fine sense of erotic tension, and actress Gedeck provides more than enough emotional resonance. This is one tricky film, but it stays with you nevertheless.

kenneth.turan@latimes.com

“Summer ’04.” No MPAA rating. Running time: 1 hour, 37 minutes. At Laemmle’s Music Hall, Beverly Hills; One Colorado, Pasadena.