This annual had a 4 part story about Roger and the gang called "Reservoir Dodge", as well as some brand new characters.
...I meant book, right? Book?
Strange and silly things lurk underneath everybody's bed, but the biggest mysteries of all are beneath Fred's! This is his first Annual appearance, though his weekly strip ran from 2007 up until 2012.
This awesome intro to one Dennis strip shows him in an epic Samurai costume! But to read the whole thing you'll have to track down a copy of the annual, or buy a personalised reprint from the Beano Shop!