diff --git a/arc-and-mutex.md b/arc-and-mutex.md
new file mode 100644
index 00000000000..d28180fa9cf
--- /dev/null
+++ b/arc-and-mutex.md
@@ -0,0 +1,7 @@
+% Implementing Arc and Mutex
+
+Knowing the theory is all fine and good, but the *best* was to understand
+something is to use it. To better understand atomics and interior mutability,
+we'll be implementing versions of the standard library's Arc and Mutex types.
+
+TODO: ALL OF THIS OMG