From that point on, some of the most unsavory aspects of the subprime lending industry came into play.

With a credit score at the low end of average, Ms. Johnson got a loan with high interest but a low teaser rate for the first two years. In February 2006 — when prices in Prince George’s County were nearing their peak — she put 5 percent down, and got a piggyback loan to cover the rest of a 20 percent down payment. Even with the teaser rate, her monthly payment was $4,175 for both loans, more than she was taking home in her paycheck each month. (That figure is based on public records; Ms. Johnson recalls the payment being somewhat lower.) But she had some savings that would help her cover the payments, she said, until she could refinance, which the bank assured her she could do very soon.

Less than a year later, she did refinance, but into a mortgage with a higher interest rate. Public records show that she consolidated the two original loans and took out an extra $20,000 in cash, but Ms. Johnson said she never saw the $20,000. (“What typically happened was people who had any home equity were targeted by mortgage brokers to refinance or buy a new home,” says Ellen Schloemer, spokeswoman for the Center for Responsible Lending. “The equity that they had would get lost in the fees and the charges that people ended up paying to get that new mortgage.”)

The new loan, from New Century Mortgage, was interest-only at first, so Ms. Johnson’s monthly payment actually decreased a bit, to $4,000. But that did not make it affordable. By her fourth payment, she was falling behind, and after less than a year, she had stopped paying altogether. She spent months trying to persuade the bank to lower the payment.

In January 2008, her loan servicer gave her a loan modification that actually increased her payments to more than $4,500.

Wanting out, Ms. Johnson hired a man named Barry Edmonds to negotiate a short sale with her lender. She began making her mortgage payments to an account he controlled. After more than two years, in May 2010, he instructed her to move out temporarily so he could ready the house for sale, she said, and she left behind furniture, photo albums and a new Jenn-Air oven. When she returned a couple of months later to pick up some belongings, she saw notices that the house was being repossessed. The locks had been changed. Shortly after that, Mr. Edmonds, and some $100,000 of her money, disappeared.

(Mr. Edmonds was fined in absentia by Maryland authorities for more than $100,000 in Ms. Johnson’s case, and did not respond to attempts to reach him by phone and email and on social media.)