Lots of spoilers follow, for both seasons, so read no further if you haven't seen them, and like to be surprised.
The second seasons starts with the immediate aftermath of John killing Danny, and Meg and Kevin helping John cover most of that up. And actually, whether the cover was of most or less of what happened on that beautiful shore doesn't really matter, because the cover-up is no more lasting than sand in the tides of the Keys.
There are in effect two parts to this second season. In the first, John lucks out, as his main adversary and obstacle to keeping all of this quiet is fortunately killed by someone else, not in the family, and with no intimate connection to it or John.
He's not so fortunate in the second part, in which Marco takes an increasing interest in the case, and gradually unravels it. Danny's friend Eric has some crucial info, and John's attempt to get Marco and Sheriff Aguirre off the case narrowly fails. The result puts the three siblings under unbearable pressure, and they finally fall apart.
I won't tell you the very ending, on the chance that you're watching the second season and have yet to see this, but I will say that one thing I didn't quite get is why Marco is so determined not only to solve this case but destroy the Rayburns in the process. His anger at Meg leaving and lying to him doesn't quite explain it - especially since she slept with him in the middle of the second season, and seemed to enjoy it, even if he thought he was being used.
But that's a small qualm in a tightly-spun, riveting narrative, with excellent flashbacks of Danny, explanations of earlier events, and a great role for Danny's son Nolan and his mother.
Highly recommended - especially if you're on Cape Cod, as I am now, and can easily imagine walking by the Rayburn's place on the beach ...
See also Bloodline Season 1: Mainlining Family