This link will lead you to a good study guide if you want to get the complete plot and other information.
In the beginning of Everyman, the central character, Everyman (that would be all of us at some point in our lives), is confronted by a mysterious character named Death who basically says, it's time for you to come with me (die). Everyman is allowed some brief time to get anyone he can to go along with him. He asks his friends, his relatives, and his material goods to go with him. When they discover where he's going they all offer excuses, some of which are lol funny. In the end, only Everyman's Good Deeds will accompany him on his final journey.
The personification of Death is a technique that's been used in other literary and musical works. One of my favorite bluegrass songs is Ralph Stanley's "O Death," in which the singer (Stanley does it A capella) directly addresses Death, who has come for him. Like Everyman, the singer-narrator in this song tries to talk his way out of Death's invitation. The song gained a larger audience after Stanley performed it in the movie "O Brother, Where Art Thou?).
Gospel has been a significant part of bluegrass music from its origins. The Stanley Brothers (Ralph and his brother Carter) had many excellent ones in their repertoire, including "Rank Strangers," "In Heaven We'll Never Grow Old," and "Angel Band." This tune is by Odell McLeod and is called "Purple Robe." It describes the scene from the Bible where Jesus is falsely accused and brought to trial before Pontius Pilate.
The focus in the song is on the inhumanity of the mob and the suffering and innocence of the accused. I first heard this song on The Vanderbilt University radio station back in the early '80s (they had a bluegrass show on Sunday afternoons at the time) and spent a few of those pre-internet days trying to learn the chords on my guitar. I really like the fine, clear guitar picking on this one, as well as the great harmonies (that mix of the high tenor and the resonating bass voice is simply outstanding).