It’s called dames rocket. It looks very similar to plox but leaves are alternate rather than opposite, toothed rather than smooth, and flowers have 4 petals rather than 5. The flowers can be white, pink, or purple.
It is becoming a very invasive plant in the U.S. and is native to Eurasia. Some states like Connecticut and Massachusetts have made it illegal to grow or transplant. It is restricted in Wisconsin for having the potential to cause significant environmental or economic harm.
If you like it but don’t want it to spread much then be careful about letting it go to seed.
One thing I do like about them, though, is that the flowers are edible and quite tasty and flavorful (for a flower).
