retrieving data from multiple nested table levels

I have a master table with a detail table linked by a foreign key (integer), this detail table then has its own child table again linked by a foreign key (integer).  So I have 3 levels

In my LINQ quey I can see the first child table but not the second.  The datacontext has the .HasMany property created so it should work.  Can anyone give me an example of a 3 level nested linq query ? Ive tried a standard table join but the 3rd level table is always empty and Ive also played around with .Include but I still cant get it to work