Two brothers-in-law. Ya’ari, a machinery designer, lives a fractious, argumentative, bustling life in an Israel he perfectly mirrors.

Yirmiyahu, a recent widower shattered by his son’s death in a friendly-fire incident in Gaza, runs an obscure cultural aid mission in Kenya. Israel repels him.

Daniela, Ya’ari’s wife, goes on a week’s visit to the remote archaeological dig that Yirmiyahu administers as part of the mission. Her purpose is to keep alive the memory of her dead sister — Yirmi’s wife — and to give support to the widower.

A. B. Yehoshua’s intent in his new novel, “Friendly Fire,” is to make Daniela an emissary between two warring visions of the author’s country, both of them his. As spoken by Ya’ari, “friendly fire” is the official euphemism that softens a reality somewhere between tragedy and lethal bungling. Spoken by Yirmi, it is something much larger: the war, fought against the Palestinians, that mortally injures the nation that fights it.

Mr. Yehoshua, Israel’s most distinguished living novelist, is a dove. But he is one who, like his fellow writers Amos Oz and Daniel Grossman, joins love for the unique qualities of his people with despair over their failure to make room politically and economically — but above all imaginatively — for the Arabs among them.

With Mr. Oz and Mr. Grossman this despair comes out as a fine anger. With Mr. Yehoshua, and it is perhaps why he is the greatest of the three (the Nobel-keepers would notice him if they still noticed Israelis), it comes out as a finer and ultimately more shattering Talmudic questioning. Not “this,” but “this and also this.”

Four years ago in “The Liberated Bride,” perhaps his masterpiece, Mr. Yehoshua coupled two alternating story lines, both featuring Rivlin, a wonderfully unquiet Israeli professor. In the larger one he battled out a whole series of seriocomic domestic crises; in the other, woven in, he took an extraordinary trip among the Palestinians, one that joined luminous discovery with a touch of the surreal. Rarely if ever has a novelist managed to make such a transformative journey between the two sides of the divide.

Purely as a novel “Friendly Fire” isn’t a match for its predecessor, though resembling it with two virtually separate stories and only the theme of separation to join them. Roughly speaking, Ya’ari, whose life we follow in Tel Aviv during the week his wife is away, is the equivalent of Rivlin at home. Yirmi, in his glimpse of the Other (he visits the Gaza site where his son was killed), is a much more approximate equivalent to Rivlin at discovery.

Mr. Yehoshua draws explicit and angry conclusions, though, instead of drawing none while leaving us to draw them. Ya’ari’s story is told in two- and three-page bursts alternating with two and three pages set in Yirmi’s Africa. The effect is a bit ramped up, as if to compensate for a fairly sluggish narrative.

Ya’ari works on tracing the wind noise in two of his elevators. He finds himself dealing with a difficult daughter and daughter-in-law and baby-sitting for a hyperactive grandson. He visits a son briefly detained because he didn’t report for reserve duty.

It is a witty portrait of a man used to feeling in command who is semihelpless in his wife’s absence. The narrative energy is high, but it is used on a low-energy narrative, and it doesn’t begin to compare with the comically searching conflicts of Rivlin’s home life.

As for Yirmi, though his story lacks the journeying immediacy of Rivlin’s travels in the West Bank, there is both dramatic and thematic tension in the week Daniela spends with him.

Her encounters with the strangeness and beauty of the African landscape, so different from the parceled-out, fought-over territory of Israel, are beautifully told. So are her dealings with the graceful and dignified African staff at the dig. The world is revealed to her as larger and more mysterious than the one seen from Israel’s embattled perspective.

But she is not prepared for Yirmi. She brings him Israeli newspapers and Hanukkah candles; he dumps them in the stove. He has fled Israel’s memories, wars and righteousness. He has no use for prophetic destinies. They have been ruined for him by the manner of his son’s death.

His account of it to Daniela is the agonizing moral and political heart of the book. Posted on a Gaza rooftop to watch for a terrorist, the son, Eyal, imprudently came down to empty his urine pail so as not to compound the outrage of occupation by leaving his waste with the occupied. His comrades, taken by surprise, shot him.

Yirmi rejects Daniela’s protest that Eyal’s motive was noble. He recalls the Arab woman who told him that her father had brought Eyal coffee, not from kindness but from the fear that if the boy fell asleep, the father could not have helped killing him. Occupation is an outrage that can’t be mitigated.

“Surely if an Israeli soldier takes over a strange house and intimidates its residents, in essence he only continues to dishonor them by suddenly risking his life to hand over a clean bucket.”

It is only part of the story, of course, and it is too much for Daniela, who, though marked by it — and by Africa — returns to the country that is her life, to light the Hanukkah candles with Ya’ari.

It is only part of the story for Mr. Yehoshua as well. But it is part of the story, and he has told it shiveringly: “This and also this.”