Using a shared folder as a Document Library in Sharepoint 365

Hi There, 

At my organisation, we are in the process of rolling out Office 365 and in particular, Sharepoint 365. 

I am trying to work out whether we can do something. Our legal team have a lot of confidential data that must be stored on our shared network drive, however they would like to be able to open it through their SharePoint site. 

Is there any way that I can set up a document library that finds its data from a network drive? So basically, the opposite way that OneDrive for Business works, e.g. folder to Sharepoint Library.

Thanks, 

Matthew