LOS ANGELES — One of the most unpredictable awards seasons in memory took another itty-bitty step toward clarity at Sunday evening’s SAG Awards, as Hollywood’s actors — who represent the motion picture academy’s largest branch — gave their highest honor to “Three Billboards Outside Ebbing, Missouri.”

Director Martin McDonagh’s dark morality tale took home three awards, including the top prize for ensemble, beating out “Lady Bird,” “Mudbound,” “Get Out” and “The Big Sick.” Frances McDormand won the lead actress award for her turn as a grieving mother who tries to spur the local police to solve her daughter’s murder, while Sam Rockwell earned the supporting actor award for his performance as a racist, dimwitted cop.

Though this year’s wide-open awards race has stymied even the most veteran Oscar prognosticators, the victories for “Three Billboards” — which follow its four wins earlier this month at the Golden Globes — could bode well for its Oscar prospects. Over the last 24 years, roughly half of the winners of the ensemble prize have gone on to win best picture at the Oscars.

That said, two of this year’s strongest contenders — Guillermo del Toro’s fantastical fable “The Shape of Water” and Steven Spielberg’s Pentagon Papers drama “The Post” — were shut out of the SAG ensemble category.

Gary Oldman won the lead actor award for his acclaimed turn as Winston Churchill in the period drama “Darkest Hour.” Allison Janney received the prize for her supporting turn as Olympic figure skater Tonya Harding’s mother in the dramedy “I, Tonya.” Both actors also triumphed at the Golden Globes.

Last year’s SAG Awards ceremony, held in the wake of President Donald Trump’s inauguration and just days after the announcement of a controversial immigration ban, was filled with raw, blistering political speeches. By contrast, this year’s show was a relatively muted affair, with the bulk of the fire directed not at Washington but at the entertainment industry itself.

On the TV side, NBC’s “This Is Us” won its first-ever award for ensemble in a drama series, with star Sterling K. Brown collecting the award for lead actor. HBO’s comedy “Veep” also won two awards for its ensemble and star Julia Louis-Dreyfus, as did its limited series “Big Little Lies,” which earned awards for Nicole Kidman and Alexander Skarsgard.