This page contains spoilers about the Heartbound ARG. If you want to solve the puzzle yourself, avoid reading this article.
In the page's source you will see:
<!-- There is only one way forward. --> <!-- Meet at the crossroads. --> <div class="Bifurcation"> <!-- Quick Foxes --> <!-- Lazy Dogs --> <!-- Not a Triffid --> <!-- ZMREIMSGNK --> </div>
This page used to be a dark page with only
<!-- Soon. --> in the source until the ARG got updated.
This div class along with the "Not A Triffid" HTML comment tell us to use the Bifid cipher. It requires a key that will be used to generate the alphabet used for decryption and a message to decrypt.
Quick Foxes and Lazy Dogs
This comment suggests that "The quick brown fox jumps over the lazy dog" phrase should be used as a key for the Bifid cipher.
After inserting the key above into the Rumkin Bifid decryptor, it translates into "DIVERGENCE."
Since this is now Phase 4, and we're starting over once again, put that right in the URL right after "Heartbound/", and you'll get the The Choice page.