diff --git a/openmc_plotter/plotgui.py b/openmc_plotter/plotgui.py
index 13dd69a..13aa91e 100644
--- a/openmc_plotter/plotgui.py
+++ b/openmc_plotter/plotgui.py
@@ -1,5 +1,6 @@
 import io
 from functools import partial
+import openmc
 
 from PySide6 import QtCore, QtGui
 from PySide6.QtWidgets import (QWidget, QPushButton, QHBoxLayout, QVBoxLayout,
@@ -308,7 +309,10 @@ def getIDinfo(self, event):
         # check that the position is in the axes view
         if 0 <= yPos < self.model.currentView.v_res \
            and 0 <= xPos and xPos < self.model.currentView.h_res:
-            id = self.model.ids[yPos, xPos]
+            if self.model.currentView.colorby == 'cell':
+                id = int(self.model.cell_ids[yPos, xPos])
+            else:
+                id = int(self.model.mat_ids[yPos, xPos])            
             instance = self.model.instances[yPos, xPos]
             temp = "{:g}".format(self.model.property_data[yPos, xPos, 0])
             density = "{:g}".format(self.model.property_data[yPos, xPos, 1])
@@ -354,7 +358,6 @@ def mouseMoveEvent(self, event):
         tallyInfo = ""
 
         if self.parent.underMouse():
-
             if domain_kind.lower() in _MODEL_PROPERTIES:
                 line_val = float(properties[domain_kind.lower()])
                 line_val = max(line_val, 0.0)
@@ -370,8 +373,25 @@ def mouseMoveEvent(self, event):
                 instanceInfo = ""
             if id == _VOID_REGION:
                 domainInfo = ("VOID")
-            elif id == _OVERLAP:
-                domainInfo = ("OVERLAP")
+            elif id < _OVERLAP:
+                # Unpack the index and find it in overlap map
+                overlap_idx = int(_OVERLAP - int(id) - 1)
+                if overlap_idx in self.model.overlap_map:
+                    universe, cell1, cell2 = self.model.overlap_map[overlap_idx]
+                    try:
+                        name1 = self.model.activeView.cells[cell1].name or str(cell1)
+                    except KeyError:
+                        name1 = str(cell1)
+                    try:
+                        name2 = self.model.activeView.cells[cell2].name or str(cell2)
+                    except KeyError:
+                        name2 = str(cell2)
+                    domainInfo = (
+                        f"OVERLAP: Universe {universe}, "
+                        f"Cells {name1} and {name2}"
+                    )
+                else:
+                    domainInfo = "OVERLAP (unknown region)"
             elif id != _NOT_FOUND and domain[id].name:
                 domainInfo = ("{} {}{}: \"{}\"\t Density: {} g/cc\t"
                               "Temperature: {} K".format(
@@ -483,7 +503,7 @@ def contextMenuEvent(self, event):
         self.menu.addAction(self.main_window.redoAction)
         self.menu.addSeparator()
 
-        if int(id) not in (_NOT_FOUND, _OVERLAP) and \
+        if int(id) not in (_NOT_FOUND) and int(id) >= _OVERLAP and \
            cv.colorby not in _MODEL_PROPERTIES:
 
             # Domain ID
diff --git a/openmc_plotter/plotmodel.py b/openmc_plotter/plotmodel.py
index 95e01f2..c454731 100644
--- a/openmc_plotter/plotmodel.py
+++ b/openmc_plotter/plotmodel.py
@@ -324,6 +324,9 @@ def __init__(self, use_settings_pkl, model_path, default_res):
         self.property_data = None
         self.map_view_params = None
 
+        # Map to be populated by overlap functions
+        self.overlap_map = {}
+
         self.version = __version__
 
         # default statepoint value
@@ -530,24 +533,34 @@ def makePlot(self, view: Optional["PlotView"] = None,
                     filter=filter_cpp,
                 )
             self.map_view_params = self.view_params_payload(view)
+                
         else:
             self.geom_data = geom_data
             self.property_data = property_data
             self.map_view_params = self.view_params_payload(view)
 
+        overlap_info, n = openmc.lib.slice_data_overlap_info()
+        self.overlap_map = {}
+        for i in range(n):
+            self.overlap_map[i] = (overlap_info[i*3], overlap_info[i*3+1], overlap_info[i*3+2])
+
         # update current view
         cv = self.currentView = copy.deepcopy(view)
 
         # set model ids based on domain
         if cv.colorby == 'cell':
-            self.ids = self.cell_ids
+            self.ids = self.cell_ids.copy()
             domain = cv.cells
             source = self.modelCells
         else:
-            self.ids = self.mat_ids
+            self.ids = self.mat_ids.copy()
             domain = cv.materials
             source = self.modelMaterials
 
+        # Normalizes so that domain only sees -3, but 
+        # overlap indices are still available in cell_ids
+        self.ids[self.ids < _OVERLAP] = _OVERLAP  # new line
+
         # generate colors if not present
         for cell_id, cell in cv.cells.items():
             if cell.color is None: