That year, in Paris, he met the New York dealer Allan Frumkin, who gave him his first American solo two years later (“Ice Box Number 1” was in it) and represented him until 1997. And by the time Mr. Saul returned from Europe to California in 1964, he was clear on what he wanted, and didn’t want, from art.

He didn’t want the pretensions — the ego, the angst — left over from Abstract Expressionism. And he didn’t want the social trappings associated with a mainstream career. (He has referred to himself as being “fairly communistic” at the time.) What he did want was to be able to paint what he pleased and to have his work noticed. And one way to get people looking was to take subjects from a source they cared about: the news.

Back home, he found that anger over the Vietnam War, which he shared, had reached high boil. And the paintings he made in response to it — seven are in one gallery on the third floor — are among the most powerful antiwar works of that era. He had, by then, traded in rough-and-ready brushwork and modulated colors for graphic crispness and a high-keyed palette. His once-loose compositions had become airtight linear tangles. Tubular figures twist and stretch in a cartoon version of Mannerist serpentinata. The formal elegance momentarily stops you, holds your eye. A beat later, content starts to come through.

It’s strong stuff. The monumental 1967 painting “Saigon” is a phantasmagoria of erotic violence so complex you almost can’t, at first, decipher it. A label painted in faux-Chinese characters clues you in: “White boys torturing and raping the people of Saigon.” Indeed that’s exactly what the scene portrays, a nightmare that is American policy in action.