Usually associated with erudite, urbane comedies, the legendary screen team of Katharine Hepburn and Spencer Tracy goes intensely dramatic in the expensive western Sea of Grass. Tracy plays cattle baron Colonel James Brewton, who staunchly opposes opening the western frontier to homesteaders. Standing steadfastly beside Brewton-at least at the beginning--is his headstrong wife Lutie (Hepburn). Eventually disillusioned by the stern implacability of her husband, Lutie leaves Brewton and goes off to Denver, where she falls in love with liberal attorney Brice Chamberlain (Melvyn Douglas), the champion of the homesteaders' cause. Upon giving birth to Chamberlain's son, Lutie confesses her indiscretion to Brewton, who takes the news with commendable restraint, even offering to accept the baby as his own. Unfortunately, the Brewtons' standing in the community is weakened by the revelation of Lutie's infidelity, causing her to leave her husband for a second time. Years later, Lutie's grown-up boy Brock (Robert Walker) drifts to the wrong side of the law, leading to his death at the hands of a posse. Though it hardly seems possible under the circumstances, Brewton and Lutie are at long last reconciled through the intervention of their daughter Sara Beth (Phyllis Thaxter). Elaborately produced in the traditional MGM manner and adroitly directed by Elia Kazan, Sea of Grass is still one of the lesser Tracy-Hepburns.
~ Hal Erickson, All Movie Guide