The title character in “Anna in the Tropics,” now playing at Barrington Stage Company, isn’t a person, but a book. And she plays a central role, thematically, narratively, even physically. The book is “Anna Karenina,” Leo Tolstoy’s winter’s tale of love – illicit, unrequited, doomed. The setting, though, in Nilo Cruz’s Pulitzer-winning play, is a Little Havana in 1920s Florida.

