Dana Joel Nicholson and Allison Collins-Elfline in the Riverbend Theatre Collective's The Last Five YearsJason Robert Brown's The Last Five Years is perhaps the best-known, most widely adored American musical that, in all likelihood, you've never heard of. Unless, that is, you're well-versed in modern musical theatre, in which case Brown's two-character, mostly dialogue-free offering probably isn't familiar so much as borderline-legendary.