John Pennington and his crew want to mine the Ponderosa land by hydraulic means. Ben is totally against this method and evicts them in short order. Hoss is given the task of telling Pennington's men to leave, but soon has a moral dilemma on his hands when he meets Pennington's beautiful sister, Emily. He soon discovers a heartbreaking secret...she's terminally ill; but their relationship soon leads to plenty of trouble for the Cartwrights.