R：取消转义JSON字符串并构建JSON对象

I am just learning to use the jsonlite library to fetch json data from a server. However in the received json response (whose structure I have no control over), there seems to be a node that I can only describe as a chunk of 'escaped' JSON data, right in the middle of the json object. How do I build a JSON object out of it? I am able to extract each such value OK but then I can't use it as is without turning it into a true JSON object.I am just learning to use the jsonlite library