I've read that book too, it's rather mindblowing.
Heaven is for Real is a biography (I think it's technically one, it's non-fiction, the father writing) about this young kid who became deathly ill, was in intensive care for I don't know how long, unconscious most of the time, but actually died (heady stopped beating I think) and was brought back to life. The whole time the father, family, and friends are praying for him and I some other events occur while the boy is under. Anyways, after the boy is healed, returns home, resumes normal life, but the parents notice him performing some strange behavior. He still acts the same, but asks many bizarre questions about Heaven, angels, etc. some stuff that kids may or may not know about, and things adults wouldn't know about. His parents ask him if he went to Heaven and he says yes, over time they gather details about his experience, he describes what it's like and such. At one part he claims he met his older sister, who was a stillborn that he didn't know about, and some other relative who died before he was born. Other stuff happens too, and I assure you the book is much more enticing than I made it appear, it's just rather late where I'm at, I'm about to go to bed. Ask someone else for more details.