Place a st marker in the top loops of the first sc on the next side. This will ensure that you find the first st to work into.
In the set-up corner, the first fpdc is worked around the first sc of the next side (= fpdc-sc1) and the second fpdc is worked around the last sc of the previous side. (= fpdc-sc2)
In the next round, the first fpdc is worked around the fpdc-sc2 of the corner in the previous round (=> is now the fpdc-dc1) and the second fpdc is worked – in front of the fpdc-dc1 just made – around the fpdc-sc1 of the same corner (=> is now the fpdc-dc2).
In each following round with a twisted corner, the new fpdc-dc1 is worked around the st that was the fpdc-2 of the previous round and the new fpdc-dc2 is worked around the st that was the fpdc-1 of the previous round of that same corner. You will most likely have to pull the previous fpdc-dc1 out from behind the fpdc you just made in order to be able to work around it properly. This is easiest done using your hook.