Node + MongoDB: params not working inside find call

I'm having trouble with params inside a MongoDB find call. If I pass the request.params.note_id I get undefined. If I call find with a number value I get a correct set of data.

Call with request.params.note_id. This returns just a blank view. Console.log prints the id correctly.

app.get("/show/:note_id", function(request, response) {
  console.log(request.params.note_id);
  return db.notes.find({
    note_id: request.params.note_id
  }, function(err, notes) {
    return response.render(__dirname + "/views/index.ejs", {
      notes: notes
    });
  });
});

Call with a fixed id of 2. This returns a correctly rendered view with the contents of note_id 2. Console.log logs correctly whatever is in the url (say "/show/22" prints 22).

app.get("/show/:note_id", function(request, response) {
  console.log(request.params.note_id);
  return db.notes.find({
    note_id: 2
  }, function(err, notes) {
    return response.render(__dirname + "/views/index.ejs", {
      notes: notes
    });
  });
});