YOU CAN SCARCELY surf the great streaming ocean without happening on a serial killer documentary or series, a fact that probably says more about us than the entertainment industry. All options, however, are not created equal. For every few quick-and-dirty procedurals, you’ll find something with real style and personality — something like The Lady of Silence: The Mataviejitas Murders, a zesty doc that walks right up to the edge of dark comedy, peers over the cliff, and takes a cheeky plunge into something weird and wonderful. Director Maria José Cuevas has located the overarching absurdity in a tragic story; in full command of her craft, she emerges as a talent well worth watching.