More than any previous season, this 13-episode story arc is character-based and internally driven by clashing agendas. Sub-plots run the gamut of neighborhood killings and gang-banger conflict, but as always The Shield also finds room for plenty of mordant wit and tension-relieving sarcasm. Like all previous Shield DVDs, this four-disc set includes informative episode commentaries from the entire cast (including Close) engaged in revealing discussions of their creative process with creator Shawn Ryan and several primary writers and directors. Best of all, the "Under the Skin" documentary is a way-above-average, 60-minute survey of The Shield's day-to-day production, offering plenty of behind-the-scenes footage and eloquent insight about the challenge of maintaining high-quality drama during a fast-paced guerilla production schedule. It's essential viewing for Shield fans and anyone considering a career in television.