Years before Watergate, the name Chappaquiddick became shorthand for political scandal. While the world was celebrating the 1969 moon landing by Apollo 11 astronauts — the legacy of John Kennedy’s belief in space exploration — the late president’s younger brother was in the midst of a devastating fall from grace.

Taking its name from the Massachusetts island where Ted Kennedy drove his car off a bridge, resulting in the death of his passenger, Mary Jo Kopechne, the movie “Chappaquiddick” dramatizes that incident and its scandalous fallout, portraying Kennedy as a complex, contradictory figure. The Kennedy dynasty has its share of admirers and critics alike, and — to the film’s credit — director John Curran and his screenwriters do not appease either camp. The result is a challenging character study, punctuated by moments of uneasy suspense and dark humor.

It is the summer of 1969, and Ted (Jason Clarke) is still reeling from the assassination of his brother Bobby a year earlier. In his late 30s, Ted is already a Massachusetts senator, and his friends believe he is positioned well for a presidential run.

After a boat race, Ted and his friends have a party on Chappaquiddick, adjacent to Martha’s Vineyard. Ted offers a ride to Mary Jo (Kate Mara), one of Bobby’s former secretaries, and off they go. An accident seems inevitable since Ted is drunk, and, sure enough, his car veers into a pond. Ted escapes, while Mary Jo drowns. The film follows Ted as he tries to pre-empt the backlash, maintaining his sympathetic public persona.

Clarke, an Australian, is no stranger to playing New England politicians: His first major role was in the Showtime drama “Brotherhood,” in which he played a Rhode Island state representative loosely based on William Bulger. As Ted, Clarke avoids caricature, portraying Kennedy as a man who loathes — yet takes advantage of — the heavy expectations that fall on his shoulders. While he experiences genuine grief over Kopechne’s death, that does not hinder his capacity for slick manipulation.

Jason Clarke as Ted Kennedy in a scene from "Chappaquiddick." (Claire Folger/Entertainment Studios via AP)

The screenplay (by Taylor Allen and Andrew Logan) strongly implies that Kennedy was still in a depressive state in 1969 and that his mind was focused more on family than politics. Bruce Dern plays Ted’s father, Joe Kennedy — the family patriarch, enfeebled by a stroke — as a hateful man whose impaired speaking ability only intensifies his anger. His disappointment in his son helps makes Ted more sympathetic: a wayward figure who wants to do good.

But Curran never lets that sympathy last long. In the moments after the accident, while Kennedy is wandering the island, Curran cuts to footage of Kopechne’s death. Drowning has a particular sound to it, and we hear Kopechne whispering in her last breaths. Curran’s depiction of this moment is harrowing in its pitilessness.

Curran films the accident from multiple viewpoints, tweaking it to accommodate Kennedy’s distortions about what happened, but these rationalizations frustrate Kennedy’s friends and advisers. As Ted’s cousin and confidante Joe Gargan, Ed Helms dials back his comic persona to create a character who knows the depths of Kennedy’s deception from the beginning. By the time Kennedy makes his famous apology on national television, Gargan cannot conceal his loathing. The film’s dark suggestion is that Gargan was a necessary enabler.

As the press descends on the island, and law enforcement unearths the nature of Kennedy’s crime — he pleaded guilty to leaving the scene of a crash — frustration gives way to exasperation. Robert McNamara (Clancy Brown), in one wry scene, tries to work out how to spin the scandal, with Kennedy not helping matters. “The Bay of Pigs was handled better than this,” McNamara deadpans.

Other Kennedy stalwarts, including JFK’s former speechwriter Ted Sorensen (Taylor Nichols), make appearances, and it is in their subtle disappointment that “Chappaquiddick” finds a certain truth about public life: No one dares say what they are really thinking. This lax attention to the truth is what allows Kennedy, ultimately, to transition from a pariah into the “Lion of the Senate,” as he became known.

Jason Clarke as Ted Kennedy, center, and Andria Blackman as Joan Kennedy in a scene from "Chappaquiddick." (Claire Folger/Entertainment Studios via AP)

Small details add to the film’s sense of authenticity. When the police chief arrives at the crime scene, for example, the morning after the accident, he is still tucking his shirt into his pants. Yet the film doesn’t dwell on Kennedy’s drinking habits, treating them matter-of-factly, and Curran implies that his relationship with Kopechne was strictly platonic.

That does not mean that “Chappaquiddick” lets Kennedy off the hook. On the contrary, the details of the crime and its coverup are even more damning than the incident’s gossipy aspects would suggest. If Curran has strong feelings about Ted Kennedy, he conceals them well.

“Chappaquiddick” provides just enough detail to allow us to draw our own conclusions, yet no viewer will think of Ted Kennedy in quite the same way. For a true-crime film about a well-documented incident, “Chappaquiddick’s” ability to preserve ambiguity is remarkable in itself.

★★★ (out of ★★★★)

Chappaquiddick

When • Opens Friday, April 6.

Where • Area theaters.

Rating • PG-13 for mature thematic material, disturbing images, some strong language and smoking.

Running time • 101 minutes.