The Maestro's Treasure (Relic Hunters 12) by David Leadbeater

Nine paintings lead the way to a priceless treasure.The Relic Hunters don’t go looking for trouble, but it always seems to find them. This time, it’s Reilly who’s the magnet. When two of his old colleagues are murdered, it turns out that Reilly is the only person alive who knows the whereabouts of a cache of stolen paintings worth millions.Using their old skills, the Relic Hunters go in search of the paintings, only to find them missing. What follows is a desperate search and then a daring heist, as the paintings are recovered.But the paintings are much more than art. They show the way to incalculable riches, a long-lost horde of treasure under the sea.The Relic Hunters, chased by Reilly’s ruthless old gang, embark on a dangerous quest for the vanished fortune.