Beetlejuice is a play about two characters: this girl named Lydia, who at the beginning of the play, her mom dies (so the first song is the funeral). Beetlejuice is a demon who can’t haunt people unless a mortal says his name 3 times. Beetlejuice finds Lydia in Invisible Reprise/On the Roof, and doesn’t realize she can see him (she doesn’t see him either at first) until he says, “That makes two of us,” and Lydia says, “Who are you??”.
What I said above, Lydia finds these two ghosts (Adam and Barbara Maitland), who bought the house Lydia’s dad is going to sell, but before they (Adam and Barbara) could do anything with the house, they died. So they partner up with Lydia to drive her dad and the people who want to buy the house out. But it doesn’t work (Banana Boat/Day-oh), and instead, the person who was originally going to buy the house says, “A genuine haunted house!! It’ll make us a fortune!!” (Or something along those lines.), so Lydia says Beetlejuice’s name 3 times, and he poofs into the part and scares everyone away. (Then some stuff happens, like Beetlejuice and Lydia scaring people (Girl Scout and That Beautiful Sound)
So some time later, Lydia’s dad, and his girlfriend come back with some thing to excorsize ghosts, but gets Barbara instead of Beetlejuice. In order to save Barbara, Beetlejuice says Lydia has to marry him (so he can become a not-ghost, and can actually kill people and all that jazz), so Lydia tricks Beetlejuice (Creepy Old Guy and some other songs), and stabs him, (which sends him back to the underworld). There was also this part where she, Adam, and Barbara (I think) went down to the underworld to go find Lydia’s mom, but instead, meet Lady Argentina (committed suicide) and a bunch of other ghosts (If I knew what I know now). Some stuff happens, Lydia returns to the overworld with Beetlejuice’s mom, the queen of the underworld (Juno) chasing her 'cause anyone who enters the underworld has to be dead, or die. Juno confronts Lydia in her house, stuff happens, Beetlejuice tries to stop Juno, Juno kills Beetlejuice, Beetlejuice comes back on a giant sandworm, and said sandworm eats Juno. Idk what Jump the Line is about tho 'cause I’ve never seen the play
https://en.wikipedia.org/wiki/Beetlejuice_(musical) (here, I found this; probably can explain better than I did)