Where No One Stands Alone - The Blake Langford Adventures, #1

Blake Langford works for the special intelligence branch of the British Government. In 1999, he was assigned to a case in Italy regarding some smuggling of blood diamonds into the country from Africa. Rachael Evans, Blake's fiancée for two years, said goodbye to him at Heathrow Airport and then vanished with no explanation. Eight years later whilst Blake is taking some long overdue leave from the Service, Rachael's sister Paula, pays him a visit at his holiday home in southern England with a message that Rachael is in trouble and needs his help.
Blake had never let go of the love he had for Rachael but had learned to live with the reality that she had gone. Now reopening long forgotten deep wounds, Blake travels across America and into Mexico to crack a diamond smuggling ring that he had stumbled upon in Italy all those years ago but this time, for Blake, the stakes are much higher.