As a quintessentially postmodern territory, Paul Auster’s fictional world is laden with suicidal doppelgangers, whom Auster employs in the third volume of his celebrated triptych The New York Trilogy, namely The Locked Room (1986), as a structuring device geared to echo a postmodern world of hermetically locked rooms. Despite the striking presence of suicide in Auster’s oeuvre, its significance as a thematic phenomenon has received surprisingly scant critical attention. The present study seeks to narrow the current lacuna by establishing a complementary relationship between suicide, the double-motif, and the characteristic postmodern mode of existence in The Locked Room. The study is carried out by applying Anthony Giddens’s psychosocial account of suicide in “A Typology of Suicide” (1966), which in addition to providing an etiological analysis, helps to contextualize the structuring device of suicidal doppelgangers in the postmodern milieu of the novel. The upshot is a coherent tripartite nexus, in which an ultimate narrative of identity loss, suicide, and the double-motif correspond to one another’s contradictions and undecidability. The aporetic indeterminacy rooted in the foregoing trio reflects the author’s literary conception of postmodern existence in the novel.