Often, mass tragedies are best understood not through bare statistics, but through personal stories of those affected. My Brother's Gift, a play by Claudia Haas based on the real experiences of survivor Eva Geiringer Schloss, tells one of these stories. I saw it on Saturday at the Black Box Theatre, and director, designer, and Black Box co-founder Lora Adams and her cast and crew have put together a spare, straightforward production that serves both as a remembrance and a call to action.