diff --git a/bin/creature-start b/bin/creature-start
index cc106a8..767cbfa 100755
--- a/bin/creature-start
+++ b/bin/creature-start
@@ -1,5 +1,8 @@
 #!/usr/bin/env node
 
+const path = x => require("../" + x);
+const immutable = path("js/immutable");
+
 const commander = require("commander");
 const program = new commander.Command();
 
@@ -9,13 +12,14 @@ const exec = util.promisify(require("child_process").exec);
 program.parse(process.argv);
 
 function setCurrentBranch(dp) {
-  return exec(`git branch|grep '\*'|sed 's/\*\s*//'`)
+  const cmd = "git rev-parse --abbrev-ref HEAD";
+  return exec(cmd)
     .then(x => x.stdout.trim())
     .then(x => Object.assign({}, dp, { currentBranch: x }));
 }
 
 function setStandardBranches(dp) {
-  return Object.assign({}, dp, { standardBranches: ["master", "release"] });
+  return immutable.set(dp, "standardBranches", ["master", "release"]);
 }
 
 function validateCurrentBranch(dp) {
@@ -26,7 +30,7 @@ function validateCurrentBranch(dp) {
   }
 }
 
-function validateFeatureBranch(dp) {
+function validateFeatureName(dp) {
   if (dp.standardBranches.includes(dp.featureName)) {
     throw `invalid feature branch: ${dp.featureName}`;
   } else {
@@ -49,13 +53,40 @@ function setFeatureBranch(dp) {
   return Object.assign({}, dp, { featureBranch: fb });
 }
 
-const x = Promise.resolve({ program })
+function gitFetch(dp) {
+  const cmd = "git fetch origin -p && git fetch origin --tags";
+  console.log(cmd);
+  return exec(cmd).then(x => dp);
+}
+
+function setMergeBranch(dp) {
+  return immutable.set(
+    dp,
+    "mergeBranch",
+    ["origin", dp.currentBranch].join("/")
+  );
+}
+
+function gitMerge(dp) {
+  const cmd = `git merge ${dp.mergeBranch}`;
+  console.log(cmd);
+  return exec(cmd).then(x => dp);
+}
+
+function toPromise(dp) {
+  return Promise.resolve(dp);
+}
+
+const x = toPromise({ program })
   .then(setStandardBranches)
   .then(setFeatureName)
+  .then(validateFeatureName)
   .then(setPrefix)
   .then(setCurrentBranch)
   .then(validateCurrentBranch)
   .then(setFeatureBranch)
-  .then(validateFeatureBranch)
+  .then(gitFetch)
+  .then(setMergeBranch)
+  .then(gitMerge)
   .then(x => console.log("x", x))
   .catch(err => console.error(err));
diff --git a/js/immutable.js b/js/immutable.js
new file mode 100644
index 0000000..c3c3e89
--- /dev/null
+++ b/js/immutable.js
@@ -0,0 +1,13 @@
+const _ = require("lodash");
+
+let lib;
+
+function set(dp, path, value) {
+  return _.assign({}, dp, _.set({}, path, value));
+}
+
+lib = {
+  set
+};
+
+module.exports = lib;
diff --git a/package-lock.json b/package-lock.json
index e736f45..fe15913 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -8,6 +8,11 @@
       "version": "2.20.0",
       "resolved": "https://registry.npmjs.org/commander/-/commander-2.20.0.tgz",
       "integrity": "sha512-7j2y+40w61zy6YC2iRNpUe/NwhNyoXrYpHMrSunaMG64nRnaf96zO/KMQR4OyN/UnE5KLyEBnKHd4aG3rskjpQ=="
+    },
+    "lodash": {
+      "version": "4.17.14",
+      "resolved": "https://registry.npmjs.org/lodash/-/lodash-4.17.14.tgz",
+      "integrity": "sha512-mmKYbW3GLuJeX+iGP+Y7Gp1AiGHGbXHCOh/jZmrawMmsE7MS4znI3RL2FsjbqOyMayHInjOeykW7PEajUk1/xw=="
     }
   }
 }
diff --git a/package.json b/package.json
index 2770ec4..d96836e 100644
--- a/package.json
+++ b/package.json
@@ -21,6 +21,7 @@
   },
   "homepage": "https://github.com/rkiel/git-utilities#readme",
   "dependencies": {
-    "commander": "^2.20.0"
+    "commander": "^2.20.0",
+    "lodash": "^4.17.14"
   }
 }