Griffin's Feather. Modern Mythology, #1

Marcus Barber is a two-thousand-year old immortal, a former Roman centurion who now works as a bounty hunter for supernatural creatures from the ancient world. When he's not pounding the pavement as a private investigator for mortal clients, Marcus chases down missing mythological creatures for the Ancients. Now, in the heat of San Antonio, Marcus must search for Nemesis's missing Griffin while trying to rescue a melting Ice Pixie from an eccentric collector.
His adventures put him on the trail of a cult that has kidnapped a Daughter of Frejya. All in a day's work. While roaming the sprawling metroplex, Marcus is also tasked with obtaining Chaac's lightning axe from the grasp of Tawhaki. Working under a tight deadline from the Ancients (who treat him as a pawn in their games), Marcus enlists a friend's help, but he has to hide the strange events and creatures.
On top of the Ancients' demands, Marcus is also hired by an assistant district attorney who wants him to track down a missing mistress... a woman with whom Marcus has his own turbulent past. By leveraging his stubbornness and his specialized skills, Marcus has to accomplish everything within 24 hours ... or else the Ancients will have his immortal soul.