From Hell: Alex Hunter 8

Pompeii, present day: Archaeologist Maria Monti is working at a new dig site. Like hundreds before her she is investigating the night that Vesuvius erupted, consuming the ancient city with choking ash, scalding steam and rivers of lava.
But she has just unearthed something that shouldn't be there, something that makes her question everything she knows about the disappearances of that fateful event.
Several hundred miles away Alex Hunter's family is holidaying in southern Italy when Mount Etna begins to shake, and ash blankets the countryside. Hideous figures are moving about in the smoke, snatching people from the streets, and scans indicate they are being taken into the core of the erupting volcano.
Hell is rising and Alex Hunter must gather a team of his most battle hardened HAWCs to take on an adversary from the very depths of hell. Nothing will stop him from rescuing Aimee and Joshua, not even the devil itself.