Hi Tehseen,
I have had several successful workouts with NPN 2nds and love them. I also do NPN 1sts. The due diligence you need regarding this is to confirm the 1st is indeed being paid and is current. This is the biggest deal breaker on the note you described. If you cannot confirm 1st is current, it's typically something to stay away from. That being said, just understand what you are getting into. The home is underwater, and the 1st mortgage cannot be confirmed, which makes for significant risk. I have completed workouts on underwater notes before, and for all my limited experience they are based on emotional equity not on equity in the property. However just understand that if equity is missing it simply removes an avenue of exit from the deal for you, meaning you cannot really "force" the borrower to resume payments, although he likely will if the modification makes financial sense.
Don't let the fact the borrower completed a BK chapter 7 scare you. I like those. It means they have less debt now, and usually more money to pay you. The thing that would kill the deal for me is the fact you have no idea if the 1st is current or not.
The lien is not necessarily stripped in a BK. It simply means the owner is no longer personally liable. You cannot go after him personally for the debt. However the 2nd mortgage still has the right to foreclose and evict the borrower from his home, so that in and of itself is leverage.
With all that being said I would avoid this deal unless you can confirm status of the 1st being paid and current. Lots of other more attractive deals out there. Don't confuse a cheap purchase price with a good deal.
Josh