diff --git a/2019/day24.py b/2019/day24.py
new file mode 100644
index 0000000..f260689
--- /dev/null
+++ b/2019/day24.py
@@ -0,0 +1,50 @@
+from grid import Grid
+
+
+DIM = 5
+
+
+def main():
+    with open("day24.txt", "rt") as input_file:
+        lines = input_file.readlines()
+    eris = Eris(value_factory=str, lines=lines)
+    eris.dumb_print()
+    print()
+
+    snapshots = []
+    while True:
+        eris.dumb_print()
+        eris.step()
+        ss = eris.snapshot()
+        if ss in snapshots:
+            break
+        snapshots.append(ss)
+    biorate = sum(2 ** i for i in range(DIM ** 2) if ss[i] == "#")
+    print(f"Biodiv rate of first repeated layout: {biorate}.")
+
+
+class Eris(Grid):
+
+    def step(self):
+        dying = []
+        infesting = []
+        for y in range(DIM ** 2):
+            x = y % DIM
+            y //= DIM
+            v = self.getv(x, y)
+            num_nears = sum(n == "#" for n in self.near_objects((x, y)).values())
+            if v == "#" and num_nears != 1:
+                dying.append((x, y))
+            elif v == "." and num_nears in (1, 2):
+                infesting.append((x, y))
+        for p in dying:
+            self.setv(p[0], p[1], ".")
+        for p in infesting:
+            self.setv(p[0], p[1], "#")
+
+    def snapshot(self):
+        return [self.getv(x, y) for y in range(DIM) for x in range(DIM)]
+
+
+if __name__ == "__main__":
+    main()