Linq To XML: Get Child XElement From Parent With Unknown Name

I currently have some XML similar to the following

<First Node>
    <Second Node>
        <Third Node>
            <Fourth Node>
               'Lots of Children in here
            </Fourth Node>
        </Third Node>
    </Second Node>
</First Node>

The issue is I know the exact names of the First, Second and Fourth Nodes. However the Third Node can be from a very wide range of possible names. I have no way to change the struct开发者_StackOverflow中文版ure of the XML when it's being created(it's coming from a third party interface).

I've attempted some linq similar to the following

tempElement = (From secondElement In xmlDoc.Descendants Select XMLDoc.Element("First Node").Element("Second Node")).FirstOrDefault

I'm using that to trim down unnecessary XML. So after that I have a XElement with

<Second Node>
    <Third Node>
        <Fourth Node>
        </Fourth Node>
    </Third Node>
</Second Node>

Then on that I'm using this linq statement to try to return just the Fourth Node

fourthElement = tempElement.ElementsAfterSelf.FirstOrDefault

This is returning me a null value. What would be the correct linq there, or is there a better way to do this?

Thanks

Just use Elements() instead of ElementsAfterSelf() - currently it's looking for elements after SecondNode instead of elements within SecondNode.