Last updated on Monday 20 January 2014 at 23:15 UK

Watch Blue's Clues Series 4 Episode 12 Online Free

Blue's Clues Series 4 Episode 12PLAY

Something very mysterious has happened – somebody built a fort in the backyard. But who? We become Blue’s Clues detectives as we hunt for clues to lead us to the mystery builder. Along the way, Mr. Salt finds a mysterious leaf and we help Steve figure out which tree it came from. Using our observation and problem solving skills, we stay hot on the trail and find the mystery builder! Can you guess who it is?

Recommended TV Series & Movies