This nonfiction book by a Swedish adventurer who befriended a stray dog on a grueling trek in South America has become an unexpected hit in the U.K. Since it was released last month, the book has topped a number of bestseller lists, and earned air time for the author--and his canine friend--on some of the country's most popular talks shows.

Book title: Arthur: The Dog Who Crossed the Jungle to Find a Home by Mikael Lindnord (co-written by Val Hudson)

First published by: Two Roads on May 19

Format: Hardcover and e-book

Author: The author is a Swedish adventurer who, during the 2015 Adventure World Championship, met a stray dog on a 435-mile hiking trail in South America. After giving a meatball to the canine, the pooch wound up following Lindnord, and his team, Peak Performance, all the way to the race's finish line.

Acquiring Editor: Kate Hewson, senior editor at Two Roads

How It’s Done: The book hit the Sunday Times bestseller list as soon as it went on sale, coming in at #7 on the hardcover nonfiction chart. More recently it claimed the #5 and #3 spots on that same list. It also reached #5 on Amazon UK's overall books chart, and has been in the top 10 of both the Waterstones and Guardian charts. The book has sold to publishers in Germany and Sweden, and deals are pending with houses in Italy and Spain.

Why They Think It’s Working: The fact that the book was based on actual events, according to Hewson, helped it capture a larger audience. She thinks this fact allowed her and her colleagues to target readers who otherwise might not be drawn to animal stories. She also believes the book was given a boost by some promotional efforts Two Roads did, specifically the two-week publicity tour the author and dog did in the U.K. During it, the pair appeared on BBC Breakfast, the U.K.’s biggest morning show. Two Roads is also using social media, in particular Facebook and Instagram, to help fans stay invested in Arthur’s journey. The author currently has 62,000 likes on his Facebook page.