This volume contains 3 complete Tommy Hambledon novels:
Drink to Yesterday is the first of the series. Young Michael Kingston, aka Bill Saunders, had a gift for languages. When he enlisted at age 17 he was drafted into the British secret service, under Tommy Hambledon, an ex-public school languages master with a sardonic humor. They were assigned undercover in Germany during World War I. The German girl that Kingston loved and Hambledon were both killed. Michael survived the war but was unable to cope with civilian life or his memories. The story is based on the experiences of one of its two authors who was the youngest member of Britain's Foreign Intelligence Office during WWI.

A Toast to Tomorrow is the second of the series. Hambledon did not die; he just lost his memory. Firmly believing that he is a German, Tommy struggles through the brutal post-war years in Germany and, like many Germans, turned to Hitler because he seemed to promise a better future. Tommy rises to a place of power in Nazi Germany, but during the Reichstag fire (set by Nazis to solidify Hitler's hold on the government) his memory returns. Horrified at what he has helped bring about, Tommy now does his utmost to undermine the Nazis while secretly sending information to the British government -- and driving them crazy because they don't know the source. Brings a touch of humor to the grim life of an undercover agent.

Alias Uncle Hugo is not the third book in the series; more like number 14. In post-WWII Europe, Tommy Hambledon is assigned to rescue a small boy, the future king of a mid-European country, from the Russian Communists. Tommy just misses the boy at his tutor's home and has to find a way to locate him at a boarding school deep inside Russian and then get him out.