March 12, 2018: Pennsylvania's 18th district is in the heart of steel country, and has long been a Republican stronghold. President Trump won the district by 20 percent, but he has seen his favorability drop since election day, and a loss for the Republican candidate will signal a warning for the GOP that they may be losing their hold nationally. The Takeaway looks at this tight race, plus a story of escape from Eastern Ghouta; the latest on the Russian nerve agent attack in the U.K.; a historic story about chemical weapons and American service-members; why Oklahoma teachers may strike; and the final piece of our "Reading the Reckoning" book club series.