Horace Winter has been working in the same bank branch for 48 years.
Never married, with no children, he lived with his mother up until her death three years prior, and now continues to reside alone in the same home.
His life has been rather unexceptional.
He doesn't have any friends, but his passion is lepidopterology - the study of butterflies and moths.
But just before his forced retirement, he is diagnosed with a very serious medical condition that makes him question the life that he has led (or hasn't), up until that point.
One day he discovers a letter that his father had written many years earlier to an ex-Corporal named Migsie Spring, and makes it his mission to get the letter to him come what may.
Even with his health rapidly deteriorating, he is given a new lease of life when he makes a friend from his neighbourhood, Amanda, and a young boy Max.
His life suddenly becomes much more adventurous than it has ever been!

I really liked Horace. He did remind me of Ove (from the book A Man Called Ove), but I actually found him to be more endearing.
When we discover that Horace was faced with a terrible tragedy that he suppressed for all these years, I felt sad for him, and it made me gain a better understanding of why he had lived the way that he had up until the point of his diagnosis.
I also enjoyed the way that Horace categorises humans as being either a butterfly or moth, according to their personality traits. It's quirky and clever.
This was an easy read, and highly enjoyable.