There are few franchises geared more for old people who don't really give a shit about movies than the Taken series, but the Da Vinci thing comes close. Tom Hanks stars as some kind of librarian who solves religious mysteries, usually thanks to the help of everyone else in the story. I saw the first one, but don't remember it very well. I think instead of making a second one they just paid for an ad campaign and everyone just assumed they went and saw it.
Now they're going for round three. Based on yet another novel by Dan Brown (Charlie's father), Inferno will tell the story of how instead of writing a poem filled with heavy metal imagery, Dante actually filled his book, The Inferno, with a bunch of symbolic messages which can only be decoded by funny-haired professionals.
Many people are buying the book, so it stands to reason that they will go see the movie. Especially since it's going to bring back the Ron Howard/Tom Hanks team that made the first so "special." So when people ask what you and your family will be doing Christmas 2015, now you know.