Bones on an Atoll

Human bones had been found on a remote atoll on the Great Barrier Reef after a large driftwood and flotsam constructed word spelling 'HELP' was seen by a tourist plane a long way that day from their usual flight path, however too late for the victim. The case is handed over to the Australian Federal Police as the atoll is over 50 kilometers off the coast and falls into their jurisdiction.
The bones are finally identified via a gold ring found on the atoll that is an induction ring belonging to a Melbourne Mafia Family. The unfortunate Melbourne Mafia member had been sent north to start up a new narcotics importation business through Townsville as the situation in Melbourne was getting too hot with warring Mafia Families and heavy police surveillance.
Federal Police based at the Townsville Office had caught two drug couriers coming in through Townsville airport. Then after confessions of who they were bringing the drugs in for, the Federal Police were too late to catch the main culprit being the unlucky Melbourne Mafia member, believing eventually he had escaped from Australia leaving them with red faces and bad media.
Knowing the Federal Police were on his trail the Mafia member had enlisted, through the help of the local criminal element, a Townsville helicopter and charter boat operator to fly him out of Australia unknown by him that the owner was the Don of the North Queensland Mafia and extremely enraged that his territory of arms and narcotics importation had been invaded by the Melbourne Mafia Family.
Instead of flying the Melbourne Mafia member out of Australia after receiving a large cash payment to do so they abandoned the victim instead on the remote atoll without food or water knowing he would unlikely be found as no one flew over or used that very remote part of the Great Barrier Reef. It would be murder almost impossible to get a conviction on.
The Melbourne Mafia send family members to Townsville to investigate the disappearance of their man which leads to Mafia Family against Mafia Family with the Federal Police then right in the middle of the action in trying to stop drug and heavy arms imports, with big shoot-outs and murder. Finally a bizarre twist at the end that will surprise.