Natasha writes a very personal anonymous letter in some sort of newspaper or periodical looking for help from the Winter Soldier who she thinks escaped, but she doesn't know he doesn't remember her, didn't escape but was sold to Hydra, and that help isn't coming. Except Clint's in Europe and he reads her letter and figures out what she actually means and takes a side-trip on whatever his mission of the hour is to track her down and be there for her.