Crock Pot Turkey Breast question

I have a 4+ pound turkey breast that I'm going to put in the crock pot with some seasoning and a little stock tomorrow morning before work. I will need to know if I cook it on high or low heat, I don't have the medium heat option and how long should I let it cook.

  I will be gone for at least nine hours and it would be another hour or so before we are ready to eat.

And I don't remember if it has the bone in or not so options for both would be good so I'm covered.

Thanks, all! 

Generally, if it's going to be that long, you'd want it on low. You can always turn it up to high for the last hour, too.

The rule of thumb I always went with was under 5 hours - high; over 5 hours - low.