Christmas may be over, but hopefully, you made some time this year to watch the most badass Christmas flick on the market: Die Hard. Technically taking place on Christmas Eve, the story of John McClane and his attempt to reunite with his estranged wife is one of the best action films ever made, but not many people are familiar with the fact that it was originally a book. Adapted from the action novel Nothing Lasts Forever, how much does Die Hard actually share with its original source material? This video below spells out all the similarities and differences between book and movie.

The YouTube channel CineFix took it upon themselves this holiday season to break down the king of Christmas action films and compare it to the novel on which it's based. Written by Roderick Thorp, Nothing Lasts Forever is actually a sequel to an earlier Thorp story called The Detective. The Detective spurned its own film adaptation starring Frank Sinatra. Thorp wrote Nothing Lasts Forever with the hope that it would be made into a follow-up film with Sinatra again in the lead role. That never happened, and when Die Hard was developed, it was altered to be a stand-alone film with no connection to The Detective.

Aside from the obvious title differences, quite a few changes were made from page to screen. The main differences mostly consist of character relationships. For starters, the hero of Nothing Lasts Forever was Joe Leland, a retired New York detective who was visiting Los Angeles on Christmas Eve to visit his daughter, Stephanie Leland Gennaro. Die Hard changed the hero's name to John McClane (Bruce Willis), made him younger, and changed his daughter to his estranged wife. In addition, though still taking place in a tall corporate tower, the book took place at the American Klaxon Oil Corporation as opposed to the Japanese Nakatomi Corporation.

A few other players were also changed; Mr. River was the boss in Nothing Lasts Forever, Al Powell is a younger cop, and Alan Rickman's Hans Gruber was originally named Anton "Little Tony" Gruber. Instead of just being a cunning thief using politics as a distraction, Anton Gruber attacked Klaxon out of political reasons because of it's shady dealings overseas. Another big change was that Leland's daughter isn't nearly as innocent as Holly Gennaro, and was actually directly involved in the company's less-than-ethical practices.

Several key events play out the exact same in the book and the movie. McClane and Leland are both armed with nothing but a pistol and a tank top, and several action scenes are the same: crawling through the air ducts, leaping off the building attached to a fire hose, dropping C4 down an elevator, etc. The major difference though is all in the tone. Nothing Lasts Forever is much darker than Die Hard. Whereas McClane saved Holly from getting pulled out the window by a falling Hans, Leland fails to save his daughter from the same situation. The novel ends with him mortally wounded and contemplating his failure.