At some point Fallon or Sam gets a phone call from France. The doctors at the clinic healed Steven from his
(extended) psychotic break, but he has signed himself out sooner than his doctors advised. (It's a fake) Steven is in a wheelchair and has memory problems. Fallon, Liam, and Sam go to Paris to collect him from Cousin Juliet's house, while Adam sits home petrified that Steven will remember all the stuff Adam pulled on him. Steven had hired a female nurse to help him regain his mobility, and Juliet suggests she accompany Steven back to the US to continue his progress. Adam is relieved when Steven comes home and doesn't recall or refer to anything that happened--it's as if he is meeting Adam for the first time. Sam is fighting his feelings all the way, but starts falling back in love with Steven. We have a big, happy family dinner welcoming him back to the fold, with Sam and Steven looking at one another lovingly. In a big cliffhanger ending, we later see Steven rolling around in bed with someone we assume to be Sam. A miracle recovery? Not quite. The viewer sees he's actually having sex with the female nurse and really,
really enjoying it.
The fake nurse (his partner-in-crime) helped S2 perfect his impersonation of Steven before fooling Cousin Juliet into believing he was 'recovered' Steven.
Fake Steven (we'll call him S2!) looks just like Steven and seems to know all the faces and most of the back-stories, but there are some major differences (not just the 'he has sex with women' thing). For starters, he's actually Australian and lapses into that accent whenever he's with his 'nurse'. Fallon asks him to accompany her on the piano, and he has to lie his way out of that (since he can't play a note). He acts so nice to Blake (at first) that Fallon actually jokes "Who are you and what have you done with Steven?", causing him to freak out.
S2 is having a really
rough time with trying to act like he's in love with Sam, since in private he's not into guys at all.
Anders notes that Steven's table manners have definitely declined since he was last at home, and Alexis is upset when he openly denounces her for 'leaving without a word' years before--seemingly having forgotten all the
secret correspondence they'd carried out over the years.
It's up to Adam to put the pieces of this scheme together, but exposing S2 would mean exposing his own role in putting Real!Steven in the sanitarium in the first place.
Adam's knowledge of the circumstances surrounding Steven's commitment are obviously more thorough than S2's, so he keeps trying to catch S2 in lies about the events leading up to his confinement. S2, feeling threatened by nosy Adam, ironically accuses Adam of being insanely jealous and wanting to take away everything he (Steven) has since he didn't grow up in the Carrington money. In another big cliffhanger, Adam goes to the sanitarium to find out more about Steven's recovery, only to come face-to-face with Real!Steven, who is still there.
I'm getting too wrapped up in this, so I'll just add that it will all end with the highly-anticipated Mackay versus Mackay slugfest, and only one Mackay will live to tell the tale. Those CW focus groups can bite me!