diff --git a/classes/ComicPress.inc b/classes/ComicPress.inc
index 67262da..d3e6747 100644
--- a/classes/ComicPress.inc
+++ b/classes/ComicPress.inc
@@ -290,34 +290,6 @@ class ComicPress {
     return false;
   }
 
-  /**
-   * Find the terminal post in a specific category.
-   */
-  function get_terminal_post_in_category($category_id = null, $first = true) {
-    $category_id = is_null($category_id) ? $this->comicpress_options['comic_category_id'] : $category_id;
-    $sort_order = $first ? "asc" : "desc";
-    $terminal_comic_query =$this->_new_wp_query();
-    $terminal_comic_query->query("showposts=1&order=${sort_order}&cat=${category_id}&status=publish");
-    if ($terminal_comic_query->have_posts()) {
-      return reset($terminal_comic_query->posts);
-    }
-    return false;
-  }
-  
-  /**
-   * Get the first comic in a category.
-   */
-  function get_first_comic($category_id = null) {
-    return $this->get_terminal_post_in_category($category_id);
-  }
-  
-  /**
-   * Get the last comic in a category.
-   */
-  function get_last_comic($category_id = null) {
-    return $this->get_terminal_post_in_category($category_id, false);  
-  }
-  
   /**
    * Get the comics necessary to build the navigation.
    * @tested
diff --git a/classes/ComicPressNavigation.inc b/classes/ComicPressNavigation.inc
new file mode 100644
index 0000000..34a6c91
--- /dev/null
+++ b/classes/ComicPressNavigation.inc
@@ -0,0 +1,37 @@
+<?php
+
+class ComicPressNavigation {
+  function init($post, $storyline) {
+    $this->post      = $post;
+    $this->storyline = $storyline;
+  }
+  
+  /**
+   * Find the terminal post in a specific category.
+   */
+  function get_terminal_post_in_category($category_id, $first = true) {
+    $sort_order = $first ? "asc" : "desc";
+    $terminal_comic_query = new WP_Query();
+    $terminal_comic_query->query("showposts=1&order=${sort_order}&cat=${category_id}&status=publish");
+    if ($terminal_comic_query->have_posts()) {
+      return reset($terminal_comic_query->posts);
+    }
+    return false;
+  }
+  
+  /**
+   * Get the first comic in a category.
+   */
+  function get_first_in_category($category_id) {
+    return $this->get_terminal_post_in_category($category_id);
+  }
+  
+  /**
+   * Get the last comic in a category.
+   */
+  function get_last_in_category($category_id) {
+    return $this->get_terminal_post_in_category($category_id, false);  
+  }
+}
+
+?>
\ No newline at end of file
diff --git a/classes/ComicPressStoryline.inc b/classes/ComicPressStoryline.inc
index a9dcfe1..3057353 100644
--- a/classes/ComicPressStoryline.inc
+++ b/classes/ComicPressStoryline.inc
@@ -3,10 +3,15 @@
 class ComicPressStoryline {
   var $_structure;
   
+  /**
+   * Create a searchable structure from a node list.
+   * @param array $structure The structure to process.
+   * @return boolean True if the structure was valid.
+   */
   function create_structure($structure) {
     $new_structure = array();
     $parent   = null;
-    $previous = null;
+    $all_leaves = array();
 
     $adjacents_by_parent = array();
 
@@ -24,6 +29,7 @@ class ComicPressStoryline {
           } else {
             $data = array();
             $leaf = end($parts);
+            $all_leaves[] = $leaf;
 
             if (count($parts) > 2) {
               $parent = $parts[count($parts) - 2];
@@ -52,12 +58,56 @@ class ComicPressStoryline {
             }
           }
         }
+        
+        for ($i = 0; $i < count($all_leaves); ++$i) {
+          foreach (array('prior' => -1, 'upcoming' => 1) as $type => $dir) {
+            if (isset($all_leaves[$i + $dir])) {
+              $new_structure[$all_leaves[$i]][$type] = $all_leaves[$i + $dir];
+            }
+          }
+        }
       
         $this->_structure = $new_structure;
       }
     }
     return is_array($this->_structure);
   }
+  
+  function _get_field($field, $id) {
+    if (isset($this->_structure)) {
+      if (isset($this->_structure[$id])) {
+        if (isset($this->_structure[$id][$field])) {
+          return $this->_structure[$id][$field];
+        }
+      }
+    }
+    return false;
+  }
+  
+  function parent($id)   { return $this->_get_field('parent', $id); }
+  function previous($id) { return $this->_get_field('previous', $id); }
+  function next($id)     { return $this->_get_field('next', $id); }
+  function upcoming($id) { return $this->_get_field('upcoming', $id); }
+  function prior($id)    { return $this->_get_field('prior', $id); }
+  function valid($id)    {
+    if (isset($this->_structure[$id])) {
+      return array_keys($this->_structure[$id]);
+    }
+    return false;
+  }
+
+  function get_valid_storyline_nav($post_id) {
+    $data = false;
+
+    foreach (wp_get_post_categories($post_id) as $category) {
+      if ($result = $this->valid($category)) {
+        if ($data) { return false; }
+
+        $data = $result;
+      }
+    }
+    return $data;
+  }  
 }
 
 ?>
\ No newline at end of file
diff --git a/test/ComicPressNavigationTest.php b/test/ComicPressNavigationTest.php
new file mode 100644
index 0000000..50e6996
--- /dev/null
+++ b/test/ComicPressNavigationTest.php
@@ -0,0 +1,18 @@
+<?php
+
+require_once('MockPress/mockpress.php');
+require_once('PHPUnit/Framework.php');
+require_once(dirname(__FILE__) . '/../classes/ComicPressNavigation.inc');
+
+class ComicPressNavigationTest extends PHPUnit_Framework_TestCase {
+  function setUp() {
+    _reset_wp();
+    $this->nav = new ComicPressNavigation();
+  }
+  
+  function testSomething() {
+    $this->markTestIncomplete();
+  }
+}
+
+?>
\ No newline at end of file
diff --git a/test/ComicPressStorylineTest.php b/test/ComicPressStorylineTest.php
index 0d3e5ac..d0461ea 100644
--- a/test/ComicPressStorylineTest.php
+++ b/test/ComicPressStorylineTest.php
@@ -35,38 +35,38 @@ class ComicPressStorylineTest extends PHPUnit_Framework_TestCase {
       ),
       array(
         array('0/1', '0/1/2'),
-        array('1' => array(), '2' => array('parent' => 1))
+        array('1' => array('upcoming' => 2), '2' => array('parent' => 1, 'prior' => 1))
       ),
       array(
         array('0/1', '0/1/2', '0/1/3'),
         array(
-          '1' => array(), 
-          '2' => array('parent' => 1, 'next' => 3),
-          '3' => array('parent' => 1, 'previous' => 2),
+          '1' => array('upcoming' => 2), 
+          '2' => array('parent' => 1, 'next' => 3, 'prior' => 1, 'upcoming' => 3),
+          '3' => array('parent' => 1, 'previous' => 2, 'prior' => 2),
         )
       ),
       array(
         array('0/1', '0/1/2', '0/1/2/3', '0/1/2/4', '0/1/5'),
         array(
-          '1' => array(), 
-          '2' => array('parent' => 1, 'next' => 5),
-          '3' => array('parent' => 2, 'next' => 4),
-          '4' => array('parent' => 2, 'previous' => 3),
-          '5' => array('parent' => 1, 'previous' => 2),
+          '1' => array('upcoming' => 2), 
+          '2' => array('parent' => 1, 'next' => 5, 'upcoming' => 3, 'prior' => 1),
+          '3' => array('parent' => 2, 'next' => 4, 'upcoming' => 4, 'prior' => 2),
+          '4' => array('parent' => 2, 'previous' => 3, 'upcoming' => 5, 'prior' => 3),
+          '5' => array('parent' => 1, 'previous' => 2, 'prior' => 4),
         )
       ),
       array(
         array('0/1', '0/1/2', '0/1/2/3', '0/1/2/4', '0/1/5', '0/1/5/6', '0/1/5/7', '0/1/5/8', '0/1/9'),
         array(
-          '1' => array(), 
-          '2' => array('parent' => 1, 'next' => 5),
-          '3' => array('parent' => 2, 'next' => 4),
-          '4' => array('parent' => 2, 'previous' => 3),
-          '5' => array('parent' => 1, 'previous' => 2, 'next' => 9),
-          '6' => array('parent' => 5, 'next' => 7),
-          '7' => array('parent' => 5, 'previous' => 6, 'next' => 8),
-          '8' => array('parent' => 5, 'previous' => 7),
-          '9' => array('parent' => 1, 'previous' => 5),
+          '1' => array('upcoming' => 2), 
+          '2' => array('parent' => 1, 'next' => 5, 'upcoming' => 3, 'prior' => 1),
+          '3' => array('parent' => 2, 'next' => 4, 'upcoming' => 4, 'prior' => 2),
+          '4' => array('parent' => 2, 'previous' => 3, 'upcoming' => 5, 'prior' => 3),
+          '5' => array('parent' => 1, 'previous' => 2, 'next' => 9, 'upcoming' => 6, 'prior' => 4),
+          '6' => array('parent' => 5, 'next' => 7, 'upcoming' => 7, 'prior' => 5),
+          '7' => array('parent' => 5, 'previous' => 6, 'next' => 8, 'upcoming' => 8, 'prior' => 6),
+          '8' => array('parent' => 5, 'previous' => 7, 'upcoming' => 9, 'prior' => 7),
+          '9' => array('parent' => 1, 'previous' => 5, 'prior' => 8),
         )
       ),
     );
@@ -79,6 +79,61 @@ class ComicPressStorylineTest extends PHPUnit_Framework_TestCase {
     $this->assertEquals(is_array($expected_structure), $this->css->create_structure($input));
     $this->assertEquals($expected_structure, $this->css->_structure);
   }
+  
+  function providerTestGetFields() {
+    return array(
+      array('parent', 1, false),
+      array('parent', 2, 1),
+      array('next', 3, 4),
+      array('next', 4, false),
+      array('previous', 4, 3),
+      array('previous', 3, false),
+      array('previous', 2, false),
+      array('upcoming', 2, 3),
+      array('upcoming', 3, 4),
+      array('valid', 1, array('upcoming')),
+      array('valid', 6, false),
+    );
+  }
+  
+  /**
+   * @dataProvider providerTestGetFields
+   */
+  function testGetFields($field, $category, $expected_value) {
+    $this->css->_structure = array(
+      '1' => array('upcoming' => 2),
+      '2' => array('parent' => 1, 'prior' => 1, 'upcoming' => 3),
+      '3' => array('parent' => 2, 'next' => 4, 'upcoming' => 4, 'prior' => 2),
+      '4' => array('parent' => 2, 'previous' => 3, 'prior' => 3)
+    );
+    
+    $this->assertEquals($expected_value, $this->css->{$field}($category));
+  }
+
+  function providerTestGetValidStorylineNav() {
+    return array(
+      array(array(1),   array('upcoming')),
+      array(array(1,2), false),
+      array(array(1,4), array('upcoming')),
+      array(array(2),   array('prior', 'upcoming', 'next')),
+      array(array(3),   array('prior', 'previous')),
+    );
+  }
+  
+  /**
+   * @dataProvider providerTestGetValidStorylineNav
+   */
+  function testGetValidStorylineNav($post_categories, $expected_navigation) {
+    wp_set_post_categories(1, $post_categories);
+  
+    $this->css->_structure = array(
+      '1' => array('upcoming' => 2),
+      '2' => array('prior' => 1, 'upcoming' => 3, 'next' => 3),
+      '3' => array('prior' => 2, 'previous' => 2)
+    );
+
+    $this->assertEquals($expected_navigation, $this->css->get_valid_storyline_nav(1));
+  }
 }
 
 ?>
\ No newline at end of file