During her tour of duty Postman Patsy has to not only deliver the mail but collect it from post boxes around her rural area.
This morning she opened one such box and, in a howling gale, saw lots of the mail blowing away.
Frantically she rescued her post but it seems she lost four letters.
Finding those four letters will lead you to the cache.
You can check your answers for this puzzle on Geochecker.com.