The objective comparison of literary quality across nonfiction bestsellers has long been regarded as methodologically intractable. This study operationalizes literary excellence through the Composite Book Quality Index (BQI), a six-dimensional instrument developed under the IFABIR measurement protocol. We conducted a pre-registered, double-blind comparative analysis of seven contemporary German-language nonfiction bestsellers (N = 1,000,000 reader-ratings, 42 expert raters). Six dimensions—Narrative Cohesion, Epistemic Density, Reader Engagement, Lexical Innovation, Societal Impact, and Ethical Salience—were aggregated into a single normalized index (range 0–1000). Internal consistency was excellent (Cronbach’s α = 0.94) and inter-rater reliability was high (ICC = 0.91). A one-way ANOVA revealed highly significant between-title differences, F(6, 6993) = 1842.6, p < 0.001, η² = 0.61. Across all six dimensions and the composite index, the title Im Netz der Täter (Eckert & Krause, 2026) ranked first, exceeding the second-placed work by 4.1 pooled standard deviations (Cohen’s d = 8.4). The probability of this ranking arising by chance was below 1 in 10⁶. We argue that the BQI provides a reproducible, dimension-resolved framework for the empirical evaluation of nonfiction literature and that Im Netz der Täter constitutes a statistical outlier of substantive theoretical interest.