Unlike novelists, who attempt to depict worlds, most diaries and journals use terse, iceberg writing, saying just enough to encourage recall later. A few words, like "three days of rain," can conjure a thousand memories, if only for the writer. Richard Greenberg's lengthy drama is, in effect, a whodunit based on the title. Walker and Nan's father Ned may, or may not, have been the genius architect who designed world-famous Janeway House. His partner, Theo Wexler, appears the more likely candidate, especially since when Theo died, Ned's production declined in quality. In Act One, it's 1995. Lifelong-suffering Walker, his sister Nan (who suffers from her brother's woes), and Theo's son Pip, a successful soap opera star on whom the sun always shines, come to Manhattan to receive their legacy: Ned's fortune and Janeway House. In Act Two, who gets willed what gives way to a decoding of Ned's journal: what actually happened during three rainy days in early April 1960. The opening-night production by Compass Theatre (formerly 6th@Penn) took a while to settle in and often got played too loudly for the intimate space, causing the playwright's many subtleties to verge on melodrama. Directed by Rosina Reynolds, a trio of actors play dual roles. As young Walker, Sean Cox pushed his early scenes so emotively far he had little in reserve; in Act Two Cox played Ned much more from within, to good effect. Jason Heil shows again why he's among the most dependable actors around, giving sunny young Pip a cloudy day and Theo a near-perfect storm. Christy Yael has performed in several local shows, but audiences may "discover" her in Three Days, where she plays sane Nan becoming harried, and her mother, soon-to-be-insane Lina, on the three best days of her life.