Thin Space by Jody Cassella

Cassella, Jody.  Thin Space.  Simon Pulse/Beyond Words. 978-1582703923. Marshall Windsor is devastated over the loss of his twin brother in a car accident where Marsh was the driver.  Marsh has been trapped in a foggy haze of grief and remorse since that fateful night. The tension builds as Marsh frantically searches for that sliver of space between the living and the dead to meet up with Austin once again and make things right.  Identical twins often switch places so all Marsh has to do is convince Austin to switch places with him one more time.  Buy multiple copies of this supernatural thriller!