Neptune King and the Artifact is the 28th book in this detective series. When Neptune's sister, Mermaid Griffith buys him a gift while on holiday in Italy, she has no idea at the time what trouble it will cause. First, her hotel room is broken into twice and her belongings ransacked, then to her dismay, she is no sooner home than her house is also broken into. The Griffiths stay at his house overnight to stop Mermaid spending all night cleaning up the burglar's mess, but they're woken during the night to an intruder in Neptune's house who manages to get away. Neptune's interest is captured instantly and volunteers his and Shark's services. Little does he know that this will be the first of many broken night's sleeps. Thanks to John Griffith being a Superintendent at Scotland Yard, Chief Inspector Daniel Dowling is assigned to the case and sets about trying to trace and identify of the burglar. However, when the burglar is found dead in Neptune's office, it takes the case up a notch and introduces an unknown entity into the field. Someone who is willing to kill to get their hands on Neptune's gift: someone who has already killed twice in Rome, and followed the burglar to London. The threat is real and deadly. No one related to or associated with Neptune is safe as this mystery killer won't hesitate to kidnap one of them to use as leverage to force Neptune to hand over the artifact. Neptune's house goes into lockdown, with new security measures and the Griffiths and Shark and his family move in with him for safety. Numerous attempts are made to get at them but to no avail, with several close calls. Neptune knows that this is no ordinary criminal they're dealing with. He's a professional. He's from Italy...draw your own conclusions.