The Being of the Beautiful: Plato's Theaeteus, Sophist, and Statesman. Translation and commentary. Chicago: University of Chicago Press, 1984.

From the publisher:

The Being of the Beautiful collects Plato’s three dialogues, the Theaetetus, Sophist, and Statesmen, in which Socrates formulates his conception of philosophy while preparing for trial. Renowned classicist Seth Benardete’s careful translations clearly illuminate the dramatic and philosophical unity of these dialogues and highlight Plato’s subtle interplay of language and structure. Extensive notes and commentaries, furthermore, underscore the trilogy’s motifs and relationships.

Online:
Amazon