As The Knife of Never Letting Go comes to a close, Todd and Viola are left in Haven. But rather than being in a safe place (as Haven was supposed to be), it turns out that this is the newest HQ for Mayor—pardon us, President—Prentiss. In other words, they've traveled all this way only to find themselves still in the clutches of the very person they've been running from this entire time. Adding to the uncertainly is the fact that Viola has been seriously wounded.
In other words, this one's a cliffhanger, Shmoopers. But so it goes in series (well, until the last book anyway). So what's up with the ending? You're just going to have to read the next book to find out.