Why don't we talk about being on this thousand-foot high tightrope? Because when you are born, grow-up, and live your entire life on the tightrope, we call it the ground.

Really dug the few seconds of Utopia's "Set Me Free" that we caught in this episode.

In means those things when it takes the ablative case. Medias res is accusative, and in + accusative means into or onto.

"in" + ablative case means in, on, or upon. "in" + accusative means into or onto. "medias res" is in the accusative case, so into is the appropriate translation.

The problem is that the phrase doesn't actually mean "into the middle *of* things." Middle is used as an adjective, describing the things into which we are going. Unfortunately, "into the middle things" makes really poor English, so we idiomatize it to make it sound nice.