diff --git a/src/service/rooms/outlier/mod.rs b/src/service/rooms/outlier/mod.rs
new file mode 100644
index 00000000..340e93e4
--- /dev/null
+++ b/src/service/rooms/outlier/mod.rs
@@ -0,0 +1,27 @@
+    /// Returns the pdu from the outlier tree.
+    pub fn get_outlier_pdu_json(&self, event_id: &EventId) -> Result<Option<CanonicalJsonObject>> {
+        self.eventid_outlierpdu
+            .get(event_id.as_bytes())?
+            .map_or(Ok(None), |pdu| {
+                serde_json::from_slice(&pdu).map_err(|_| Error::bad_database("Invalid PDU in db."))
+            })
+    }
+
+    /// Returns the pdu from the outlier tree.
+    pub fn get_pdu_outlier(&self, event_id: &EventId) -> Result<Option<PduEvent>> {
+        self.eventid_outlierpdu
+            .get(event_id.as_bytes())?
+            .map_or(Ok(None), |pdu| {
+                serde_json::from_slice(&pdu).map_err(|_| Error::bad_database("Invalid PDU in db."))
+            })
+    }
+
+    /// Append the PDU as an outlier.
+    #[tracing::instrument(skip(self, pdu))]
+    pub fn add_pdu_outlier(&self, event_id: &EventId, pdu: &CanonicalJsonObject) -> Result<()> {
+        self.eventid_outlierpdu.insert(
+            event_id.as_bytes(),
+            &serde_json::to_vec(&pdu).expect("CanonicalJsonObject is valid"),
+        )
+    }
+