Broadway musicals have always sought to entertain with custom-made songs designed to move the story along, songs that are full of catchy melody and clever lyrics that hook you into wanting to hear them again and again.

Lately, however, musicals have come with the musical appeal built in, through the use of popular hit songs the audience already knows. Those songs are then refitted into a plot, sometimes comfortably, sometimes not. But the formula has had huge successes: Mama Mia using songs of '80s pop group ABBA and Jersey Boys, which tells the story of Franki Valli and the Four Seasons using their music.