We're giving America's favorite condiment a swirl in this deliciously drippy episode. Seafood dishes like hot lobster rolls and blue crab spaghetti get dressed in robes of butter at restaurants in Boston and New York while bakeries in San Francisco, Washington, DC and Atlanta bring butter to new heights in their flaky pastries. We've also got butter in places you never even thought of -- on top of knish sandwiches and melted into mochi.

The Smithsonian Museum in Washington DC is probably the biggest museum in the world, with nine separate locations on Washington's historic Mall, this is an extraordinary storehouse of the weird, the macabre and the downright terrifying. This programme goes into the vaults of the Postal museum to reconstruct the story of a mail robbery that went badly wrong and find a poignant reminder of the Hindenberg disaster. In the forbidding basement of the natural History museum we have a close encounter with a Giant Squid and puzzle over the fish some call the missing link. We look into the revealing details of the birth of a nation and tell the inside story of the death of a president.