Q.What Is Wrong Here?
Last year I built a new raised bed. We had great success with the garden. This year I planted 4 tomato plants, beans, a few onion sets and 2 eggplants. I mixed marigold and basil in the garden. It’s been a month of heat and drought so I have been watering well a couple times a week. The last few days one, and only one, of my tomato plants started to droop and curl on the new growth. It is quickly getting worse. I have never had this problem. My plan is to remove it to a separate pot and see what happens. Can you tell me what may be going on?

Certified GKH Gardening Expert
Either, moles or voles are present. These creatures will destroy a garden before your eyes.
Here are some articles that will help you to control them:
https://www.gardeningknowhow.com/plant-problems/pests/animals/mole-control.htm
https://www.gardeningknowhow.com/plant-problems/pests/animals/vole-control.htm