Understanding of pulmonary mechanics is essential to understanding mechanical ventilation. Typically, clinicians are mindful of peak and plateau pressures displayed on the ventilator and lung compliance, which is decreased in lung disease such as idiopathic pulmonary fibrosis (IPF). Decreased lung compliance leads to elevated peak and plateau pressures. We present a patient with IPF undergoing mechanical ventilation after cardiac arrest. Despite low lung compliance, he had normal peak and plateau pressures due to the presence of flail chest and increased chest wall compliance. This case highlights the role chest wall compliance plays in total respiratory system compliance and pulmonary mechanics.