Lightning network is well complicated and has lots of code to deal with transactions within
the network so if a banking hub (in theory) goes bad you can broadcast to the BTC network
to get you money back
See white paper https://lightning.network/lightning-network-paper.pdf
what people are not getting about lightning is that just because you deposit your
money at the bank in a ledger it is not the banks money (You can get it back) and the bank has to forward
it own money out from a separate ledger on to the next bank before Alice gets paid
See http://forum.cryptolivecap.com/posts/t31-Lightning-Network
Dave is this case is the bank or watch