Hi, Mark Armon, this is a common English idiom. "Take a turn for the worse" means to start to get worse. Example: "It appeared that she was going to get well; then, unfortunately, she took a turn for the worse." Another example: "My job was going quite well; then last week things took a turn for the worse." It basically means that something was going well, but it suddenly started to get worse. I hope this helped! -Kyle

This is an expression- as if the plans are laid out on a road- "took a turn" for the worse, means that the situation got worse. One can also say "take/took a turn for the better". Meaning things got better