Karen McDonough of Quincy, Mass., was enjoying her tea one morning in the dining room when she saw something odd outside her window: a group of people gathering on her lawn. A man with a clipboard told her that her home no longer belonged to her. It didn't matter that she'd been paying her mortgage for 17 years and was current on it. She was a nurse with a good job and had raised her kids there. But this was a foreclosure sale, and she was going to lose her house. McDonough had fallen victim to what's called a zombie second mortgage. Homeowners think these loans are long dead. But then the loans come back to life because they get bought up, sometimes for pennies on the dollar, by debt collectors that then move to collect and foreclose on people's homes. On today's episode: An NPR investigation reveals the practice to be widespread. Also, what are zombie mortgages? Is all this legal? And is there any way for homeowners to fight the zombies? You can read more about zombie second mortgages online at: npr.org/zombie This episode was hosted by Chris Arnold and Robert Smith. It was produced by Sam Yellowhorse Kesler. It was edited by Jess Jiang with help from Bob Little. And it was fact-checked by Sierra Juarez. Engineering by Robert Rodriguez with an assist from Patrick Murray. Alex Goldmark is Planet Money's executive producer.Help support Planet Money and get bonus episodes by subscribing to Planet Money+ in Apple Podcasts or at plus.npr.org/planetmoney.