Outlaws of Time #2: The Song of Glory and Ghost by N.D. Wilson

My name is Glory, and we must save Peter's life or everything is lost. Sam may be destined to kill The Vulture, but The Vulture's assassins have gone back in time to kill Peter as a baby. The Ghost said I'm a time-walker and has given me the power to locate Peter, but Sam and his arms will need to protect me. A girl named Samra joined us on our last jump, after her father overpowered and tied our friends, and I'm not sure what we should do about her. I don't really know what I'm doing as a time-walker, and we have less than a day to save Peter. If Peter dies at birth, all of the Father Tiempos in time will disappear, and Sam will also die. Then, there will be nothing left in the world able to stop The Vulture from destroying the world as we know it. 

You need to read The Legend of Sam Miracle before reading this one, or it won't make any sense. Time traveling and alternate realities make the series challenging enough as it is. Honestly, be prepared to think and use your imagination or you'll be lost. The setting jumps to vastly different times and places in history, and sometimes in between. Glory is more of the focal point than she was in book one. She's been advising Sam before this time, but now she is dictating their new missions. This book reveals more about her past. Peter is the main priority, since his death will allow The Vulture to destroy the world. To complicate things, The Vulture is amassing an army of creatures without loyalty; they will become uncontrollable once they're unleashed. Once again, Sam's arms have their own subplots. Cindy, the snake controlling his left arm, only wants to kill, while Speck is the more cooperative snake controlling his right arm. Sam is learning to better deal with their personalities.