Grace's mom, Kathleen isn't home yet - where do you think she's gone? Judging by the spoilers for season 4 episode 16, could it possibly have to do with Marshall's secret?
Check out the spoilers for season 4 episode 17 of Secret Life, "Suddenly This Summer":
- George's paranoia gets the best of him when he thinks Anne has developed feelings for someone he knows, someone close to him.
- Grace nervously awaits her mom's return - but return from where? From Africa?
Source: Secret Life Spoilers