diff --git a/scraper/src/libretexts2zim/client.py b/scraper/src/libretexts2zim/client.py
index a448e94..e444a02 100644
--- a/scraper/src/libretexts2zim/client.py
+++ b/scraper/src/libretexts2zim/client.py
@@ -57,6 +57,21 @@ class DekiTree(BaseModel):
     root: DekiPage
     pages: dict[str, DekiPage] = {}
 
+    def sub_tree(self, subroot_id: str) -> "DekiTree":
+        """Returns a sub-tree, starting at give page id"""
+        new_root = self.pages[subroot_id]
+        tree = DekiTree(root=new_root)
+        tree.pages[new_root.id] = new_root
+        children_to_explore = [*new_root.children]
+        while len(children_to_explore) > 0:
+            child = children_to_explore[0]
+            children_to_explore.remove(child)
+            if child.id in tree.pages:
+                continue  # safe-guard
+            tree.pages[child.id] = child
+            children_to_explore.extend(child.children)
+        return tree
+
 
 class LibreTextsMetadata(BaseModel):
     """Metadata about a course."""
diff --git a/scraper/src/libretexts2zim/generator.py b/scraper/src/libretexts2zim/generator.py
index b2d4000..18a1d4f 100644
--- a/scraper/src/libretexts2zim/generator.py
+++ b/scraper/src/libretexts2zim/generator.py
@@ -45,6 +45,8 @@ class ContentFilter(BaseModel):
     page_id_include: str | None
     # If specified, page with title matching the regex are excluded.
     page_title_exclude: str | None
+    # If specified, only this page and its subpages will be included.
+    root_page_id: str | None
 
     @staticmethod
     def add_flags(parser: argparse.ArgumentParser):
@@ -72,6 +74,12 @@ def add_flags(parser: argparse.ArgumentParser):
             metavar="REGEX",
         )
 
+        parser.add_argument(
+            "--root-page-id",
+            help="ID of the root page to include in ZIM. Only this page and its"
+            " subpages will be included in the ZIM",
+        )
+
     @staticmethod
     def of(namespace: argparse.Namespace) -> "ContentFilter":
         """Parses a namespace to create a new DocFilter."""
@@ -80,6 +88,9 @@ def of(namespace: argparse.Namespace) -> "ContentFilter":
     def filter(self, page_tree: DekiTree) -> list[DekiPage]:
         """Filters pages based on the user's choices."""
 
+        if self.root_page_id:
+            page_tree = page_tree.sub_tree(self.root_page_id)
+
         title_include_re = (
             re.compile(self.page_title_include, re.IGNORECASE)
             if self.page_title_include
diff --git a/scraper/tests-integration/test_client.py b/scraper/tests-integration/test_client.py
index b556c94..b4f45f9 100644
--- a/scraper/tests-integration/test_client.py
+++ b/scraper/tests-integration/test_client.py
@@ -7,7 +7,7 @@
 )
 from zimscraperlib.image.probing import format_for
 
-from libretexts2zim.client import LibreTextsClient, LibreTextsHome
+from libretexts2zim.client import DekiTree, LibreTextsClient, LibreTextsHome
 
 
 @pytest.fixture(scope="module")
@@ -40,6 +40,14 @@ def nb_root_children() -> int:
     return 6
 
 
+@pytest.fixture(scope="module")
+def page_tree(
+    client: LibreTextsClient,
+    deki_token: str,  # noqa: ARG001
+) -> DekiTree:
+    return client.get_page_tree()
+
+
 def test_get_deki_token(deki_token: str):
     """Ensures we achieve to get a deki_token"""
     assert deki_token
@@ -62,15 +70,18 @@ def test_get_root_page_id(
     assert client.get_root_page_id() == root_page_id
 
 
-def test_get_page_tree(
-    client: LibreTextsClient,
+def test_get_page_tree_pages(
+    page_tree: DekiTree,
     minimum_number_of_pages: int,
-    deki_token: str,  # noqa: ARG001
+):
+    assert len(page_tree.pages.keys()) > minimum_number_of_pages
+
+
+def test_get_page_tree_root(
+    page_tree: DekiTree,
     root_page_id: str,
     nb_root_children: int,
 ):
-    page_tree = client.get_page_tree()
-    assert len(page_tree.pages.keys()) > minimum_number_of_pages
     assert page_tree.root.id == root_page_id
     assert len(page_tree.root.children) == nb_root_children
     assert page_tree.root.title
@@ -78,6 +89,22 @@ def test_get_page_tree(
         assert child.title
 
 
+def test_get_page_tree_subtree(
+    page_tree: DekiTree,
+):
+
+    # 28207 = https://geo.libretexts.org/Courses/Coastline_College/An_Introduction_To_Geology_-_Coastline_College/01%3A_Understanding_Science
+    subtree1 = page_tree.sub_tree("28207")
+    # 4 = "1. Understransding Science" + "1.1: What is Science?"
+    #  + "1.2: The Scientific Method" + "1.3: The Study of Geology"
+    assert len(subtree1.pages.keys()) == 4
+
+    # 28196 = https://geo.libretexts.org/Courses/Coastline_College/An_Introduction_To_Geology_-_Coastline_College
+    subtree2 = page_tree.sub_tree("28196")
+    # 94 is number retrieved in Oct. 2024, might change
+    assert len(subtree2.pages.keys()) == 94
+
+
 def test_get_home_image_url(home: LibreTextsHome):
     """Ensures proper image url is retrieved"""
     assert home.welcome_image_url == "https://cdn.libretexts.net/Logos/geo_full.png"
diff --git a/scraper/tests/test_generator.py b/scraper/tests/test_generator.py
index f8cf4a7..e1f12cd 100644
--- a/scraper/tests/test_generator.py
+++ b/scraper/tests/test_generator.py
@@ -59,6 +59,7 @@ def deki_tree() -> DekiTree:
                 page_title_include=r"^1\..*",
                 page_title_exclude=None,
                 page_id_include=None,
+                root_page_id=None,
             ),
             ["24", "25", "26", "27", "28"],
             id="include_1",
@@ -68,6 +69,7 @@ def deki_tree() -> DekiTree:
                 page_title_include=r"^2\..*",
                 page_title_exclude=None,
                 page_id_include=None,
+                root_page_id=None,
             ),
             ["24", "29", "30", "31", "32"],
             id="include_2",
@@ -77,6 +79,7 @@ def deki_tree() -> DekiTree:
                 page_title_include=None,
                 page_title_exclude=None,
                 page_id_include="26,27,28",
+                root_page_id=None,
             ),
             ["24", "25", "26", "27", "28"],
             id="include_3",
@@ -86,6 +89,7 @@ def deki_tree() -> DekiTree:
                 page_title_include="ground",
                 page_title_exclude=None,
                 page_id_include=None,
+                root_page_id=None,
             ),
             ["24", "29", "30", "33", "34"],
             id="include_4",
@@ -95,6 +99,7 @@ def deki_tree() -> DekiTree:
                 page_title_include=r"^1\..*",
                 page_title_exclude="Tree",
                 page_id_include=None,
+                root_page_id=None,
             ),
             ["24", "25", "26", "28"],
             id="include_exclude_1",
@@ -104,6 +109,7 @@ def deki_tree() -> DekiTree:
                 page_title_include=None,
                 page_title_exclude="Tree",
                 page_id_include="26,27,28",
+                root_page_id=None,
             ),
             ["24", "25", "26", "28"],
             id="include_exclude_2",
@@ -113,6 +119,7 @@ def deki_tree() -> DekiTree:
                 page_title_include="ground",
                 page_title_exclude="^2",
                 page_id_include=None,
+                root_page_id=None,
             ),
             ["24", "33", "34"],
             id="include_exclude_3",
@@ -122,6 +129,7 @@ def deki_tree() -> DekiTree:
                 page_title_include=r"^1\..*",
                 page_title_exclude="tree",
                 page_id_include=None,
+                root_page_id=None,
             ),
             ["24", "25", "26", "28"],
             id="include_exclude_case_insensitive",
@@ -131,6 +139,7 @@ def deki_tree() -> DekiTree:
                 page_title_include="tree",
                 page_title_exclude=None,
                 page_id_include=None,
+                root_page_id=None,
             ),
             ["24", "25", "27"],
             id="include_case_insensitive",
@@ -140,10 +149,31 @@ def deki_tree() -> DekiTree:
                 page_title_include="^tree",
                 page_title_exclude=None,
                 page_id_include=None,
+                root_page_id=None,
             ),
             [],
             id="include_no_match",
         ),
+        pytest.param(
+            ContentFilter(
+                page_title_include=None,
+                page_title_exclude=None,
+                page_id_include=None,
+                root_page_id="25",
+            ),
+            ["25", "26", "27", "28"],
+            id="root_page_id",
+        ),
+        pytest.param(
+            ContentFilter(
+                page_title_include=r"^1\.1.*",
+                page_title_exclude=None,
+                page_id_include=None,
+                root_page_id="25",
+            ),
+            ["25", "26"],
+            id="root_page_id_and_include",
+        ),
     ],
 )
 def test_content_filter(