Who is Trying to Silence Penny? Penny Thorton's dreams of being a park ranger start to unravel her first week on the job when she finds a dead bear in Yellowstone's backcountry. Shots are fired as she runs away, but once she tells the authorities, all evidence evaporates. Penny's aunt Iris, who is bent on eradicating an invasive species of daisy from the park, puts that mission on hold when more bears are killed and she become entangled in the mystery. After several attempts on Penny's life, she and Iris learn to trust no one not even their friends.