Thoughts while reading:
Okay, first sentence is definitely a hook, but I'm lost as far as setting and character (who even said the first sentence, and why?). There is a big difference between confusion and suspense. Don't confuse your audience for very long. It is a big turn off for me. I HATE being confused. Constantly guessing what will happen next, yes; confused, no.
Dialogue is really good and pacing of details is not bad either. Lots of points from me there. But the word discovered? *wince* Who talks like that? It's 'caught,' not 'discovered.'
Okay, lots of 'telly' details about the mom. At first it was fun, by the end it was annoying. Pick your favorites than 'show' me the rest.
Whao! Character 'telly' information overload on all of them now. For a first draft it is fine, you need to know and establish these things about your characters for yourself, but in a book you have plenty of time to show/tell us these things as we go rather than spoon feeding it to us all at once. Just like the mom, pick your favorite telly details and show us the rest. Don't tell us something you are planing to show and visa versa.
Ex: I can tell by his friends' reactions after the mom left that Sam's attempt to butter her up was fake and annoying, so I don't need it in the narration.
Watch the tags. Your dialogue is good enough that it should be easy to use said or drop a few tags all together and still get your point across.
Over all impression:
It felt completely different than your first submit style wise and it was harder to tell where you are going with all this, but I loved the characters and loved the scene and had a lot of fun reading it. Sentence style was good and the scene flowed pretty well.
Keep it up!