It turns out that when he was a child Abe's mother was slain by a angry slave merchant because she and Abe both had interfered with the sale and beating of several slaves. Abe swore to hunt the fellow down and kill him. When he attempts to do so his plans go awry as he discovers that the merchant is in fact one of the living dead. He is rescued from his folly by a vampire hunter and sets out on the road of hunting and killing vampires.
In the course of events as he's battling vampires all over town he learns that slavery is actually a front, or partially so, for the secret vampire nation that dwells throughout the Union. They feed on the slaves in secret.
Time passes and Abe sets aside his axe to fight slavery (in order we suspect to weaken the vampire nation) and thus the civil war begins. It gets even weirder after that as vampire armies...immune to the sun because of some lip balm or some such...take up the grey and attack union armies. Silver is gathered from all over DC to stop them at Gettsburg where they are defeating the Union.
The action sequences in the movie are really cool; the figure of tall Abe wielding an axe and lopping open vampires is pretty cool. There is a scene in Louisiana where Abe and his pals battle the super bad guy vampire, its really well done. Some crazy wagon rides too. But the overall vampire nation/civil war vampires/Gettsburg/sunblock scenes are rather out of whack.
The movie is fun, with good action, setting and the first part of the story is actually a pretty cool yarn; but the latter half of the movie goes off reservation and ends up in very weird alternate history. Of course what did I expect with the title Abe Lincoln Vampire Hunter.
I give it two trolls!