The Promise of Plasma – Until new drugs are found to treat COVID-19, one of the more effective treatments has been plasma therapy. Bill Whitaker reports on how doctors are taking the blood plasma of COVID-19 survivors, and the virus-fighting antibodies in it, to create the life-saving therapy. Spilling Across the Border – Lesley Stahl reports on raw sewage that is entering Southern California's coastal lands and waters from Tijuana, Mexico, just over the border. Perseverance – In the most ambitious Mars rover mission yet, NASA hopes to launch Perseverance this summer to find evidence of ancient life on the "Red Planet." Anderson Cooper reports.