is a terrifying ghost story for anybody over the age of 12.

"This book is wonderful: funny, frightening, compulsively page-turning and all in all a rattling good read," says cartoonist and author Martin Rowson.

Tim thinks that science explains everything, that what you see is what you get - like being able to do an ollie on your skateboard.

His sister Rox doesn't agree. She believes in séances and ghosts and wants nothing more than to meet an evil spirit. Pity the evil spirit!

When their family moves into medieval Greenwich Abbey in south east London, Rox is immediately convinced that it's haunted. She's sure somebody died a horrible death there and decides to investigate - demanding Tim's help of course.

But Tim knows how to shut her up. He has a plan. He sets out to examine the "evidence" scientifically. Soon he realises he only has one solid fact - a ghost is trying to kill him...