The Mortal Instrument Series is Very Good--City of Bones, City of Ashes, and City of Glass.
"thousand years ago, the Angel Raziel mixed his blood with the blood of men and created the race of the Nephilim. Human-angel hybrids, they walk among us, unseen but ever-present, our invisible protectors.
They call themselves Shadowhunters.
The Shadowhunters obey the laws set down in the Gray Book, given to them by the angel: their mandate is to protect our world from the interdimensional parasites they call demons, who travel from world to world, razing and destroying everything in their path. Theirs is also the task of keeping the peace among the warring Downworlders: the human-demon crossbreeds we know as warlocks, vampires, werewolves, and faeries.
In their duties they are aided by the mysterious Silent Brothers. Their lips and eyes sewn shut, the Silent Brothers rule over the City of Bones, the necropolis below the streets of Manhattan that holds the dead bodies of slain Shadowhunters. The Silent Brothers keep the archival records of ever Shadowhunter ever born. They also watch over the Mortal Instruments, the three divine objects the Angel Raziel gave to his children. One is a sword. One is a mirror. And the last is a cup.
For a thousand years, the Nephilim have protected the Mortal Instruments. But that was before the Uprising, the civil war that almost tore the Shadowhunters' secret world apart. Though Valentine, the Shadowhunter who started the war, is long dead, the wounds it left behind have never healed.
Fifteen years have passed since the Uprising. It's August in New York; the streets blistering with heat. Rumors run rampant through Downworld that Valentine is back, at the head of an army of Forsaken warriors.
And the Mortal Cup has gone missing..."
There is really no way to describe these books. ^That is the opening story that I found on the website. In each of the three books one of the three mortal instrements is stolen, and they go deeper and deeper uncovering this whole story in attempts to find them. Once you start the first book, you wont be able to put it down. It's one of my favorite series.