Dominic Riley starts off seeming to be a fairly straight-up detective; however, it turns out that his father was killed by the original Grendel, Hunter Rose.  He first gets attached to the case of the new Grendel in town ( Christine Spar) when she kills Yoshi Onagawa, one of the flunkies of Tujiro XIV, a vampire slaver.   He investigates Onagawa's murder.
 
He starts looking for Christine Spar, who is publicly well known as an authority on the previous Grendel; the New York police, who are sure Spar is Grendel, have also been sharing their information with the San Francisco police.  He can't find her, but does find Brian Li Sung, and asks him about Spar (in a somewhat rude manner).  Brian brushes him off, and Riley starts to get suspicious about him.
 
Christine and Brian later battle Tujiro and another of his flunkies, Niccolo.  Riley bursts into the building only to find that Tujiro and Spar have just escaped, but sees Niccolo running away, and gets some other cops to arrest him.  Brian is still there, and Riley arrests him.
 
Riley sweats Brian pretty hard at the police station, but Brian doesn't give in.  He stays quiet about Christine.  Riley becomes more and more aggressive and belligerent.  He's definitely playing the "bad cop."  He's eventually ordered to let Brian go, but tells him to stay in town.
 

To his shock, Brian leaves for New York the same day.  He immediately follows him.  His issues with Brian are no longer just professional, they're personal.  When he finds Brian, he pistol-whips him viciously in an out-of-control rage.  When Spar finds out what happened, she puts on her Grendel garb, determined to have revenge.
 

In an innovative issue with almost no text, she secretly baits and harasses him over a period of hours.  She sends a drone to fly at his head, appears in a mirror and then disappears, puts coals in his pockets, throws a dead bird at his head, drops a street sign near him, blows up his taxi, pushes him off the subway platform, sends a bum to annoy him, and drops bricks and a tub of goo on him.  All this time he gets more and more frantic, as it becomes clear that someone is after him.  He's like a mouse in a maze.  He starts shooting wildly, but only hits a display of books she wrote.  He runs away and takes some time to cool down in a bar.  Getting his courage up once more, he leaves, only to be dragged by Christine into a nearby alley.  He tries to draw his gun, but she cuts off his fingers and rams him in the jaw with the blunt end of her fork.  He lies on the ground, before her, having been humbled.  Then she stabs him in the chest in cold blood.