When details finally came out about “Underworld: Awakening,” my heart sunk a little. True, the second installment wasn’t very good, and the third was a prequel, but I was still looking forward to seeing further adventures of the vampire, Selene (Kate Beckinsale). As it turns out, she’s the only returning cast member. Everyone else is gone from the project, leaving her the one tie to a series (seemingly) well past its prime. “Awakening” also clocks in at under 90 minutes, making the first film’s two hours seem like days in comparison.

The plot this time around is told to us in the form of exposition. After “Evolution,” humans discovered that lycans (werewolves) and vampires exist, and decided to wage war against both mythical creatures. They decided that genocide was the only option, and all but wiped out both species. So, how did Selene manage to survive? Well, she was captured by some scientist folks who decided to keep her alive, but frozen, for the past twelve years. Michael (previously portrayed by Scott Speedman), her vampire-lycan hybrid lover, has presumably died.

So, you’ll be unsurprised to find out that Selene eventually escapes from her prison, fits back into that catsuit that she has grown accustomed to, and begins trying to find out just what the world has become in her absence. Of course, she still believes that Michael is still alive, so she sets out on a quest to find him. Meanwhile, she’s also getting random visions flashing in front of her. It turns out, as anyone who has seen Evolution will have assumed, she has given birth to a daughter, Eve (India Eisley), and the two are linked via their sight. She can see what Eve can see if they are close to one another.

The villain this time around is the head of the scientists, a man named Jacob (Stephen Rae). I suppose the humans are also the bad guys, as they want to kill any vampire they come across, although the one human whose name we learn, a detective named Sebastian (Michael Ealy), ends up helping Selene. She’s also eventually joined by another vampire, David (Theo James). Lycans also still exist, and they end up becoming more frequent as the film progresses after a plot twist is revealed that you’ll probably see coming from a mile away, if you haven’t already guessed it.

There isn’t really a central plot that’s worth discussing. “Underworld”: “Awakening’s” screenplay reads as both lazy and very loose. It’s hard to even reflect back on it and try to remember key moments. It doesn’t care about secondary characters (they’re plot devices), and it doesn’t care for its main one all that much either, although Beckinsale’s Selene does have to show a tad bit more emotion than in previous installments. But not much more.

Essentially, we’re here for the action scenes, which serve both as the main material as well as the glue that holds it together. In what is probably the most action-packed and gory iteration in this series, “Underworld”: “Awakening” certainly doesn’t have many boring moments. There’s no substance to the plot or characters, but if you’re watching the fourth “Underworld” film, chances are you don’t care about that kind of thing. You’re here to see Kate Beckinsale in a tight leather catsuit running around, doing flips off walls, shooting at anything that moves, and doing it all with a blue tinge. You get that with “Awakening.”

Initially, I couldn’t quite put my finger on why I still didn’t have a great time with this film. It did most of the things it needed to right, and was overall quite exciting. But it lacked substance, and I don’t just mean in its story and characters. Even at its worst point (“Evolution”), the “Underworld” series has always maintained some depth to the world that the characters inhabit. An entire back story was mapped out, and we understood the history of both supernatural clans. “Awakening” seems dedicated to both ruining and ignoring all of that previous work.

Here is a film that’s premise involves the destruction of the majority of both species’ members. Presumably, artifacts and historical documents were also destroyed, rendering much of the back story unknown to the survivors. Those who do know, like a man named Thomas (Charles Dance), have no proof of it and have no need to bring it up. The world is no longer an “Underworld” one; instead, it’s just a generic action movie with vampires and werewolves. All of the work that went into the crafting of this universe is destroyed with “Awakening.” It almost seemed like directors Måns Mårlind and Björn Stein went with this story just so that they didn’t have to include any depth, even if that depth is what made “Underworld,” well, “Underworld.”

Maybe I’m overthinking things. Like I said, you’re watching “Underworld: Awakening” to see Kate Beckinsale in a bunch of physics-defying action scenes while dressed in her character’s signature leather outfit. You get that here. The action scenes are slick and well-made, the lycans look better than they ever have before, and the ending sequence, involving at least three distinct battles, is satisfactory, even if the ending as a whole promises much more than it delivers. I did have a good time, even if this installment completely ignores all of the history and back story of its universe. This is a movie for the “Underworld” fans. If you’re one of them, you’ll have a good time here. Newcomers will want to start at the beginning. If you aren’t a fan, this one has less depth and more action than earlier iterations, so make your decision accordingly.

[http://www.youtube.com/watch?v=bor9gCAB9qM&feature=fvst]