Amb. Dr. Francis Kirimi Muthaura is well known in Kenya as a career civil servant, and internationally as a diplomat par excellence. In his five decades of public service, he achieved the rare feat of serving under the five post-colonial regimes of Mzee Jomo Kenyatta, Daniel arap Moi, Mwai Kibaki, Uhuru Kenyatta and William Ruto. He launched his career in the early 1970s as a junior officer in the provincial administration and exited in November 2022 as Chairman of the Kenya Revenue Authority Board. His vision has been a dedicated and committed public service to Kenya, the East African region and the world, for which he won accolades and awards from diverse institutions. A Moving Horizon is the life journey of Amb. Dr. Muthaura, spanning from his childhood on the slopes of Mt. Kenya to his retirement from public service. The book follows the career of Amb. Dr. Muthaura as he rises through the ranks, taking on diplomatic assignments in European capitals and at the United Nations before assuming a leading role in the re-establishment of the East African Community. It tells about his return to the Kenya Civil Service where he rose to the office of Head of the Civil Service and Secretary to the Cabinet. The reader is then taken through his heartrending moment when he is indicted for crimes against humanity at the International Criminal Court (ICC). The journey of Amb. Dr. Muthaura exemplifies focus, loyalty, resilience, commitment, and patriotism - inspiring both aspiring and current civil servants.