The Thieves of Ostia, by Caroline Lawrence

As a one-time student of Greek & Roman Studies, I've been thrilled to see this series inspire several children in my branch to learn about Roman culture and mythology.

The Thieves of Ostia is the first book of the seventeen-volume Roman Mysteries series.  It introduces a group of four friends who work together to solve the mysterious death of a pet dog.  I found the story to be predictable, but enjoyable, populated by likeable but fairly flat characters.  As this book represents Lawrence's first foray into novel-writing, I'm curious about whether her writing is stronger in later volumes once she's had a chance to develop her craft.