Led Zeppelin - Fool in the Rain
I was still very early in my Zeppelin fandom when I first heard this song on the radio, and I have to admit that my reaction was along the lines of "holy shit, this is awesome!!" Unfortunately, every time I heard the song for weeks, they never said the name of it, so my attempt to find out the name of it so I could buy the CD was futile. Asking several friends who knew Zeppelin didn't work either, probably since my attempt to describe the song was probably not good, especially since there is no main vocal line to grab on to and identify to them as such. Eventually, I found out the name, although I don't remember how, but In Through the Out Door quickly became a part of my CD collection right away, and over 20 years later, this is still one of my favorite LZ tunes.