Old Debts

A jealous regret goes overboard. His rage and anger curse all who bound him to a watery fate. The grave welcomed him with open arms as he was considered the devil's spawn. But he had other designs. Woe to be to whomever unraveled his intentions.
Years drifted by without pause or care. Until...
When he was discovered. The same place, but a little worse for wear. And as for all the warnings, they were long since forgotten. Save for a medallion, of Celtic origin, scripted with the cause and cure.
Driven by gold's fever, it was hastily snatched.
Death to be who unleashes the beast, woe to be the brethren of those who slain him. Be it by line of blood or consent, they will die. And suffer in the same grim way he was so drowned.
Enter the hero, whose continual prayers for redemption may go unchecked, but not unnoticed. He is called to the funeral of his brother, the one who unwittingly unleashed the monster. Our hero, by name of Jake, is, was Chicago's most notorious contract assassin. It has been said neither bullet, blade nor blunt can harm he. Or so goes the legend.
And now he lays to rest his little brother, the last of his clan, save for Madison, his teenage niece. And now Jake, doing the admirable thing, cares for her.
The monster, call him Shannon O'Dowd is exacting is particular brand of revenge. The body count grows. Detective Diana Lancaster has her own particular paranormal talent investigates. She sees beyond what the boys in forensics proclaim and prove.
What are called the Neglected, they prefer abandoned. All heap sob stories onto Diana, who complies with conditioned British resolve and with her own particular brand of sardonic wit.
And then there is Jake. It is not the abandoned who follow him, but rather those who unceremoniously crossed over by Jake's munitions.  
Needless to say, he is a fly in some rivals' ointment. To them, Jake has outstayed his welcome, to others, a lasting testament to an old regime.
But Shannon O'Dowd will be not be denied his blood thirst, his form of reckoning. The murders continue, more grisly than before.
The monster is immune to destruction save from the power of faith. The decay of the old gods made provisions that only a man of faith can bring down the cursed. Followed by releasing the fire serpent, a old legend that has been lost in the chronicles of time.
And this begins our series...