Murder at the hospital

Marc, a 12-year-old blind boy, breaks his leg and goes to the hospital. But there, strange things happen and Marc finds himself looking for a murderer with his two best friends and his dog, Zoop. Only then do questions occur to him. Where is his mom? Why did the murderer say Marc's long lost grand-father's name? There's only one way to find out: find the murderer. And that may not be as simple as it sounds...