[TYPO3-mvc] Child object values

[Matt Janus]

I am just starting out with extbase and slowly getting my head around
it but I am having  a problem of access values of child object.

each mark will contain an over all mark, number of question answered
etc. it will then reference a value object that will contain
information regarding the module such as module title, module code and
the number of exam questions for that module.

I have attached the an image to help explain (hopefully it will show up).

In the fluid template I can access the values of the module by -
{mark.moduledetail.code}

The question I have, is how can I access this value in the mark
controller? I'm sure its something very simple but it has been driving
me mad for days.

Any help, or pointers would be most appreciated.

Thanks

Matt