When a retired art professor and his second wife show up at the country estate once owned by his first wife, no one is happy. Not the professor, who is sickly, not his lethargic wife or the love-struck step-daughter or the doctor who drinks too much. Even the kitchen help is annoyed. Unhappiest of all is the misanthropic uncle, and he’s armed. The makings of a prime-time soap? Nyet! This is the stuff of great Russian drama. Anton Chekhov’s “Uncle Vanya,” a production of Penobscot Theatre Company, opens tonight and plays through March 26 at the Bangor Opera House. The upshot: Indolence and lazy minds make for classic soap opera. You know what Chekhov said: If there’s a gun, it has to go off. Vodka optional. Tickets required: 942-3333.