What two messages does Pip receive in chapter 52?

Wemmick sends Pip a note indicating that now may be a good time to escape with Magwitch and get him out of the country.

In the meantime, Pip gets another letter, this one by an anonymous author, telling him to come down to the limekiln in the marshes that night. Once again, Pip goes to his hometown and walks out to the marshes.