In 2010, Democrats controlled everything, from the White House, to Congress, to the governor's office to the Wisconsin state Legislature. Republicans were pushing back, and the Tea Party was in full swing. But something was changing in American politics and in Wisconsin — and Scott Walker used the high-speed rail plan to seize the moment.

Before Gov. Scott Walker canceled the high-speed rail line that would have connected Madison to Milwaukee in 2010, Wisconsin bought two trains from a Spanish company named Talgo.

The story of these trains is messy. And in a way, they're the physical reminder of the debate Wisconsin had almost a decade ago.

Because the story of "Derailed" happened over the course of decades, there's a lot there, and a lot we didn't get to. Some of it, like Gov. Jim Doyle's role in ending the train, is still discussed today. Other stuff, like the 2016 Olympics connection, seems to have been lost to history. Here are some of the questions we didn't get to in "Derailed.