Peter Diamond is tasked to run security for a wedding. Seems a bit beneath his extraordinary detective talents, as well as his title as head of Bath's CID, but this isn't your run-of-the-mill ceremony: the bride and groom belong to families on opposite ends of the law - and someone is trying to sabotage the nuptials by taking out a hit on the father of the bride.

As a New Year begins in Bath, Ben Brace proposes to his long-term girlfriend, Caroline, the daughter of notorious crime baron, Joe Irving, who is coming to the end of a prison sentence. The problem is that Ben's father, George, is the Deputy Chief Constable. A more uncomfortable set of in-laws would be hard to imagine. But mothers and sons are a formidable force: a wedding in the Abbey and reception in the Roman Baths are arranged before the career-obsessed DCC can step in.

Peter Diamond, Bath's head of CID, is appalled to be put in charge of security on the day. Ordered to be discreet, he packs a gun and a guest list in his best suit and must somehow cope with potential killers, gang rivals, warring parents, bossy photographers and straying bridesmaids. The laid-back Joe Irving seems oblivious to the danger he is in from rival gang leaders while Brace can't wait for the day to end. Will the photo session be a literal shoot? Will Joe Irving's speech as father of the bride be his last words? Can Diamond pull off a miracle, avert a tragedy and send the happy couple on their honeymoon?