diff --git a/mediashelf/providers/plex.py b/mediashelf/providers/plex.py
index 527d4f1..182f2ea 100644
--- a/mediashelf/providers/plex.py
+++ b/mediashelf/providers/plex.py
@@ -197,6 +197,17 @@ class PlexProvider:
                 ))
 
         kind = "movie" if library.kind == "movie" else "episode"
+
+        # Plex sometimes returns an episode with no parentRatingKey even though
+        # it knows the show and the season number (seen on Firefly in TV Show
+        # Archive: 15 episodes, parentGuid present, parentRatingKey null).
+        # Without a season id the whole season used to be dropped from the
+        # report, so synthesize a stable one from show + season number.
+        season_id = row.get("parentRatingKey")
+        if season_id is None and row.get("grandparentRatingKey") is not None \
+                and row.get("parentIndex") is not None:
+            season_id = "%s:s%s" % (row["grandparentRatingKey"], row["parentIndex"])
+
         return Item(
             provider_item_id=str(rk),
             kind=kind,
@@ -215,7 +226,7 @@ class PlexProvider:
             parts=parts,
             show_id=str(row["grandparentRatingKey"]) if row.get("grandparentRatingKey") is not None else None,
             show_title=row.get("grandparentTitle"),
-            season_id=str(row["parentRatingKey"]) if row.get("parentRatingKey") is not None else None,
+            season_id=str(season_id) if season_id is not None else None,
             season_number=_opt_int(row.get("parentIndex")),
             episode_number=_opt_int(row.get("index")),
         )
diff --git a/mediashelf/queries.py b/mediashelf/queries.py
index f330134..3779870 100644
--- a/mediashelf/queries.py
+++ b/mediashelf/queries.py
@@ -200,7 +200,11 @@ class Query:
             flags.append("duplicate")
         if (d.get("provider_view_count") or 0) > 0 and not d.get("watch_count"):
             flags.append("history_gap")
-        if (d.get("part_count") or 0) > 1:
+        # A season has one part per episode, so part_count > 1 is normal there;
+        # only flag genuinely extra files (a movie held twice, or a split episode).
+        parts = d.get("part_count") or 0
+        if (d["kind"] == "movie" and parts > 1) or \
+           (d["kind"] == "season" and parts > (d.get("episode_count") or 0)):
             flags.append("multi_part")
 
         return {
diff --git a/tests/test_ingest.py b/tests/test_ingest.py
index 573343c..295d0a8 100644
--- a/tests/test_ingest.py
+++ b/tests/test_ingest.py
@@ -119,3 +119,22 @@ def test_refuses_history_from_a_different_plex_server(db, cfg, monkeypatch):
     result = ingest.Ingest(db, cfg, media, history).run("full", "manual")
     assert result.status == "failed"
     assert "different plex server" in (result.error or "").lower()
+
+
+def test_episodes_without_a_parent_rating_key_still_build_a_season(scanned):
+    """Plex omits parentRatingKey on some episodes (Firefly, live). Dropping
+    them silently lost a whole 15-episode season from the report."""
+    season = scanned.one(
+        "SELECT i.*, p.title AS show FROM media_item i "
+        "JOIN media_item p ON p.id = i.parent_id "
+        "WHERE i.kind='season' AND p.title='Orphan Show'")
+    assert season is not None, "season was dropped for want of a parentRatingKey"
+    assert season["episode_count"] == 5
+    assert season["size_bytes"] == 5 * 2 * 10**9
+    assert season["season_number"] == 1
+    assert ":s1" in season["provider_item_id"], "expected a synthesized season key"
+
+
+def test_no_orphan_episode_warnings(scanned, rescan):
+    r = rescan("full")
+    assert not [w for w in (r.warnings or []) if "no season" in w]
diff --git a/tests/test_rules_and_api.py b/tests/test_rules_and_api.py
index bf8fba2..37b5509 100644
--- a/tests/test_rules_and_api.py
+++ b/tests/test_rules_and_api.py
@@ -207,3 +207,14 @@ def test_completion_flag_is_false_for_plex_only_history(scanned):
     from mediashelf import queries
     scanned.execute("UPDATE watch_event SET percent_complete = NULL")
     assert queries.history_has_completion(scanned) is False
+
+
+def test_multi_part_flag_is_not_set_on_ordinary_seasons(client):
+    """A season has one part per episode; flagging that as multi_part put a
+    meaningless badge on every TV row in the grid."""
+    data = client.get("/api/v1/items?page_size=500&kind=season").get_json()
+    seasons = [i for i in data["items"] if i["kind"] == "season"]
+    assert seasons
+    bogus = [s for s in seasons
+             if "multi_part" in s["flags"] and s["part_count"] <= (s["episode_count"] or 0)]
+    assert not bogus, f"{len(bogus)} seasons flagged multi_part with no extra files"
diff --git a/tools/mockserver.py b/tools/mockserver.py
index 8cc2c4b..ff2e382 100644
--- a/tools/mockserver.py
+++ b/tools/mockserver.py
@@ -96,6 +96,25 @@ def _build(seed=7):
                 })
                 ep_rk += 1
 
+    # A show whose episodes carry no parentRatingKey — Plex really does this
+    # (Firefly, in the live TV Show Archive). The season must still be built.
+    orphan_show = "990"
+    shows.append({"sectionKey": "3", "ratingKey": orphan_show,
+                  "guid": "plex://show/orphan", "type": "show", "title": "Orphan Show"})
+    for ep in range(1, 6):
+        episodes.append({
+            "sectionKey": "3", "ratingKey": str(ep_rk), "guid": "plex://episode/%d" % ep_rk,
+            "type": "episode", "title": "Orphan Ep %d" % ep, "index": ep,
+            "grandparentRatingKey": orphan_show, "grandparentTitle": "Orphan Show",
+            "parentRatingKey": None, "parentIndex": 1,
+            "addedAt": NOW - 900 * DAY, "duration": 45 * 60000, "viewCount": 0,
+            "Media": [{"videoResolution": "1080", "Part": [
+                {"id": 70000 + ep_rk,
+                 "file": "/mnt/titan4/TVArchive/Orphan Show/S01/E%02d.mkv" % ep,
+                 "size": 2 * 10**9}]}],
+        })
+        ep_rk += 1
+
     # ── Tautulli history ───────────────────────────────────────────────
     watchable = [m["ratingKey"] for m in movies] + [e["ratingKey"] for e in episodes]
     row_id = 1