Charlie has died (in mysterious circumstances involving triplets)…
The episode opens with the family returning from the funeral. It turns out that there is no will, so it looks like Alan has the Beach House, the piano and the cars.
An previously unknown older half-brother (new character) shows up and asserts his right on Charlie’s estate. A Judge’s order dictates that Alan and the half-brother must share the house.
And there we are, back to Two and a Half Men. An ongoing gag would be Charlie’s ex-girlfriends showing up to claim part of the estate.