As a creative mantra, "write what you know" doesn't always work: It can result in myopic self-absorption as much as personalized insight. But Third Trinity, the new solo show from Miami wunderkind Teo Castellanos, cemented the value of autobiographical writing in its spartan production at the Light Box at Goldman Warehouse. His frequent partner in the theater of the avant-garde, Tarell Alvin McCraney, directed Castellanos, though it felt like he was directing a bustling ensemble: Castellanos played 23 characters, ranging from himself and his two brothers to petty drug dealers, priests, junkies, and his own grandmother, in a therapeutic and adventurous journey spanning three decades. Local audiences connected with the show's excursions into Cocaine Cowboys territory — the script, with its Goodfellas-like Mob menace, was originally penned as a screenplay — not to mention the vintage Dade County images projected onstage and the cauldron of South Floridian dialects Castellanos combined. The show could easily play elsewhere in the country, but it will always be ours.