After weeks of professional and personal setbacks, Carter leaves the ER - and Abby - behind to join the equally troubled Kovac on a relief mission in war-torn Africa. But upon arrival, the hellish conditions, lack of supplies and rampant disease soon have him clamoring for the comforts (and even the chaos) of Chicago. In time, these unlikely allies realize they are exactly where they're needed most, especially after a skirmish between local rebels and the African government's Army triggers the docs' bloody battle to save a child caught in the crossfire.