Find out about secret tunnels past and present. Secret bunkers, underground cities and war-time tunnels - it's all in here. Then read a story about treasure, a secret tunnel and a secret exit.

This fun non-fiction reading book, with exciting colour photos and illustrations, will appeal to all older struggling readers. It focuses on a popular topic to provide interest for an older age range and, as part of one of the higher sets of the Thunderbolts series, will engage struggling readers and promote further progression. As with all Thunderbolts titles, the book includes a non-fiction section and a fiction story.