diff --git a/web_view.py b/web_view.py
index 058f09e..1bbfbc9 100755
--- a/web_view.py
+++ b/web_view.py
@@ -237,10 +237,15 @@ def trip_list() -> str:
 
 @app.route("/trip/<start>")
 def trip_page(start: str) -> str:
+    """Individual trip page."""
     trip_list = build_trip_list()
     today = date.today()
 
     trip = next((trip for trip in trip_list if trip.start.isoformat() == start), None)
+
+    if not trip:
+        flask.abort(404)
+
     return flask.render_template(
         "trip_page.html",
         trip=trip,