This open-label, single-arm Phase II clinical trial investigates the combination of lattice radiation therapy (LRT) and subsequent consolidation chemoimmunotherapy for patients with unresectable stage III locally advanced non-small cell lung cancer who only achieved limited tumor regression after standard neoadjuvant chemoimmunotherapy induction. LRT, a spatially fractionated radiotherapy technique, generates interleaved high- and low-dose zones inside tumor tissue to enhance local anti-tumor activity while minimizing radiation toxicity to surrounding healthy chest organs. Eligible participants will complete standardized thoracic LRT targeting primary lesions and involved lymph nodes following institutional contouring rules and dose restrictions. Consolidation chemoimmunotherapy will be initiated shortly after the end of radiotherapy. The study will continuously monitor all treatment-related and immune-related adverse events, evaluate therapeutic efficacy via regular imaging scans, and collect long-term survival data. Trial results will provide clinical evidence about the clinical value and safety profile of LRT plus consolidation chemoimmunotherapy for this high-risk LA-NSCLC subgroup with insufficient response to prior neoadjuvant systemic therapy.