Build the first four ingredients in an iced Collins glass. Top with the Angostura so it floats on top and slowly cascades toward the bottom.
This drink works with pretty much any ginger beer but the ginger spiciness of the Fever Tree really makes the drink come alive.
I created this drink while working at Michael Symon's Roast in Detroit, MI. I served it for a couple of days before I came up with the name. The rusty color of the drink made me think of the skeleton keys that opened the old locks in my grandparents house.