The Escape by David Baldacci

John Puller is a criminal investigator for the military. His brilliant brother Robert, once a rising star in the intelligence community, is now imprisoned at Leavenworth for treason. John gets word that a storm has knocked out the power at the prison, the backup system has mysteriously malfunctioned and his brother has escaped. Though his commanding officer orders John to stay away from the case, a trio of powerful men convinces him to try to find his brother and he's soon partnered with a female intelligence agent named Knox that he's not sure he can trust. John is convinced his brother was framed for treason, that someone was trying to kill him in prison--which is why he escaped--and that someone powerful has a master plan. It's quite the page turner as the two brothers separately then together work to clear Robert's name and find out who has been pulling all the strings.

This is part of a good series by Baldacci that also included Zero Day and The Forgotten.