Trying to remember a book?!?

OK so I still remember a little bit about the book Im trying to remember. The book cover was gray and kinda looked like.. steel flooring. Uhh the Father was crazy and trapped his Wife and his son and his daughter in a.. Mansion type place to protect his kids from a made up disaster. The family had another brother but the brother and the grandmothers "Died" but thats what the father told the family even though it really didn't happen. Also the dad was doing experiments on his daughter to make a child thats.. like a clone. And they I think had to stay there for.. 15 years until it was safe to see land again. Also when they did escape they lived happily ever after but when the escaped the house it was insane like.. the father was chasing the second oldest son (the one who didnt get lost with the grandmother) And the daughter I think it was it may have been the clone. And the mansion they were protected in blew up! So have any idea what this book was called?! PLEASE HELP ITS IRRITATING ME!