Barstad's work is a close critique of the history of interpretation of Second Isaiah (chs. 40 - 55 [66]) and its alleged Babylonian provenance. He demonstrates convincingly that the 19th century arguments in favor of the Babylonian provenance are in fact quite empty and closely connected to a thesis of a second Isaiah. On the one hand there is a perceived need to dissociate a sixth century second Isaiah from the prophet Isaiah ben Amoz in eighth century Jerusalem. On the other hand is the erroneous 19th century belief that the land of Judah was uninhabited except by illiterate peasants during the period of the exile and thus unable to produce a major prophetic or literary work (despite the book of Lamentations).
In Barstad's opinion, one of the telling signs of the untenable nature of this hypothesis is the emergence of a Trito Isaiah, which is born out of an inability to associate later chapters in this section of Isaiah with the alleged Babylonian provenance.
Though Barstad appears to be in favor of a Judean provenance for Second Isaiah, he does not set out to demonstrate this; he rather seeks to demonstrate that the foundation on which the Babylonian consensus is built will not stand up to critique.