The Unicorn Murder or Victoria's Revenge — Gerald Anderson

After a lifetime of reading British history and British Whodunits, Palmer Knutson, the famous Norwegian-American sheriff of Otter Tail County, Minnesota, and his lovely wife Ellie, take the trip of a lifetime and visit England. They drive around the country, scaring British motorists as they continue to drive on the wrong side of the road.  They are fascinated by British language, food, and customs, and are looking forward to getting to London to take in a few West End musicals.  Unfortunately, while in Cornwall, the owner of their small hotel is murdered.  He is found at a prehistoric site with what looks to be a unicorn horn thrust through his body. Knutson is forced into a "busman's holiday" to help the local detective inspector solve the case.  Their progress is frequently slowed by the fact that one of them speaks "English" and the other speaks "American."  This is the fifth in the series of Palmer Knutson mysteries.