The game starts much like the first Devil May Cry -- Dante is sitting in his not-yet-opened shop and approached by someone named Arkham, who unleashes a flurry of demons to assault him as per Vergil's request. After the attack, a giant tower pops up in the middle of the city. Sensing Vergil, Dante makes his way to the tower in what could be described as a pissing contest of epic proportions.
While making his way into the tower, Dante is met by the game's female lead -- a girl on a motorcycle with a gigantic rocket launcher named Kalina-Ann. The girl's name is Lady, but she is also referred to as Mary. She seems to enjoy Lady more. As the game goes on, you learn she's Arkham's daughter and is driven by her desire for revenge against him, because he killed her mother.
Dante and Lady make their way back to the top of the tower (Vergil apparently fell into a deep crevasse) where Dante convinces Lady to let him handle things. She gives him her powerful weapon, Kalina-Ann. Once at the top, Dante enters the demon realm and confronts Arkham who seems a bit too overwhelmed by the power of Sparda. During their battle, Vergil reappears and teams up with Dante to fight the enemy. Arkham is weakened and expelled from the demon realm and back to the top of the tower. Lady is waiting for him there and gets her revenge. It's awesome.
In the demon realm, Dante and Vergil battle over who has the right to own Sparda's sword, the Force Edge. Dante wins, eventually. Defeated, Vergil decides to remain in the demon realm with his half of the amulet -- after the ending credits he is seen facing off against Mundus, the enemy from the first Devil May Cry. We can assume Mundus defeated Vergil and turned him into the demon Nelo-Angelo.
Dante and Lady meet outside the tower and form a partnership of sorts, naming Dante's shop Devil May Cry because of the tear Dante shed over the loss of his brother.
So did the combat. DMC3 offered the ability to switch between two weapons and two guns on the fly, which unleashed a flurry of combos that took the hyper-action of the genre to a whole new level. There was also a class system -- where you can raise your proficiency at using melee weapons, guns, blocking attacks, using evasive maneuvers, slowing time, or creating a double of yourself. Adding the classes to the different variety of weapons made the game much more customizable and approachable for players of all preferences. To this day, only God of War games can even compare to the wild style of fighting and chaotic nature of Devil May Cry 3's battle system. If you haven't played it, we assure you, it's that good.
There's one catch, though: you need to be a very, very, very good player at Devil May Cry games to play this game. It's incredibly difficult. Capcom had to release a "special edition" with a lowered difficulty level (among numerous other changes, including the ability to play as Vergil). It's that hard. It's that good. The camera is still wonky, but it gets in your way less. Dante reprises his role as a one-line spitting anti-hero. As far as the franchise goes, the only game Devil May Cry 4 has to compare itself to is this one. This is the cream of the crop as far as DMC goes and as far as action games go.