Max and Olivia Freeze are former agents of MI6.
By former, I definitely mean 'was' as in the past, long ago. They each became operatives around the same time; the Second World War was raging and England needed intrepid people of both sexes to go behind enemy lines to help defeat the Nazis and both Max and Olivia, not yet a couple, volunteered. Thrown together by the dangers they each faced, they fell in love and went on to be married. With the ending of the conflict but the beginning of the Cold War, both remained active in the intelligence work although on more of a part-time, as-needed basis. When not on active mission, Max and Olivia maintained a cover identity as a vicar and his young wife.
Over the many years that are mentioned only briefly, the two produced two children and enjoyed a very pleasant life of ministering to their flock of congregants except when the Government called and they were pulled away to take part in very exciting missions. Eventually old age would come knocking and as both reach their 80th birthdays, having spend 60 of those as a couple, they had long since retired from both the ministry and the Ministry. When an unfortunate incident with their motorbike-and-sidecar brought unwanted attention of the authorities, each of their children offered to take them in but both Max and Olivia had no desire to be 'looked after' by their children and having a fair amount of money put aside (it seems working part-time for MI6 can be profitable), they entered a retirement home.
That is where we find both of them, happy but frankly more than a little restless after so many, many years of action and excitement. They had, regretfully, transitioned "from being eighty-five-years-young to eighty-seven-years-old". They would certainly have remained in the facility until their final breaths were it not for something they read in the newspaper. That something will bring them out of retirement, in their opinion, and back into action.
The action in question will pit them against an extremely resourceful and ever so deadly foreign agent by the name of Claudia. Her part in the various adventures - really one long adventure with numerous side trips - will be so important she almost earned the right to be in the name of the series. Claudia is definitely not the same age as Max and Olivia, being considerably younger and far more energetic. She is as interesting as she is resourceful - and she is very resourceful. [She gets her own series later]