Tunnels is a 6-book series with 6 primary works first released in 2007 with contributions by Roderick Gordon, Brian Williams, and Brian Williams.
2007 • 29 Readers • 660 pages • 3.3
2008 • 15 Readers • 659 pages • 3.8
2009 • 3 Readers • 577 pages • 5
2010 • 2 Readers • 527 pages
2011 • 8 Readers • 443 pages • 2.8
2013 • 3 Readers • 402 pages • 5