“Orphans” begins with a quiet scene of childlike glee and ends with a pained, howling, almost primal scream. Those moments bookend a character study that careens from one dramatic extreme to another: There are sudden bursts of violence, moments of humor and catharsis and a complicated power struggle between two men, both of them provisional parental figures with penchants for crime. This is a challenging, gritty, emotionally taxing piece of theater, expertly directed by Marianne McLaughlin, and it’s the best, most complex show of the Spokane Civic Theatre’s ongoing season. The play is set in a grubby Philadelphia row house, likely sometime in the 1980s, where two brothers live in relative squalor. The oldest brother is named Treat (Billy Hultquist), who has been raising his younger brother Phillip (Maxim Chumov) since their mother died and their father abandoned them at a young age. Treat is a petty thief, leaving the house every morning to pilfer jewelry from people he encounters on the streets. Phillip’s world doesn’t extend beyond the old swashbucklers he watches on TV and his view from the living room window – he’s been convinced by his older brother that he’s deathly allergic to outside air, so he never leaves the house.