Having two faces is nothing new to Mary. It would have been in her job description, had she ever been shown one one. The difference is that in the past, one of the two faces was false, a front that she put up to hide her true intent. Now both faces are real. She never knew that she could live each moment constantly in two states, one of joy at her new engagement, and one of paranoid terror.

John constantly surprises her with his tenderness, and Sherlock … she would have expected him to be distant and cold, but he isn't. After the fire, he is nothing but warm to her. His enthusiasm for helping with the wedding is unexpected and very useful. But at other times, she suspects him of knowing everything and staying close only to keep an eye on her.

But no, it can't be. Sherlock is clueless. He is so preoccupied with trying to be John's friend that he can't see past his own nose. Unfortunately, there are others who see things too well. She was contracted to kill John and Sherlock, and yet she saved John from the bonfire. She has declared her loyalties, she's switched sides. Now whoever is out there watching knows that she is their enemy. She needs to know more about her enemy. She needs to know what's going on. But how can she research things with Sherlock constantly asking her about the color of the bridesmaids dresses, and what icing to put on the cake?

Distracting him is incredibly easy, however. She pulls Sherlock aside one morning and says, "I'm worried about John. You know that he doesn't really like all of this wedding planning. It suffocates him. He needs to get out a bit. Like a dog that has been in the house too long. He needs someone to run him. Do you think that you might be able to do that for him?"

"Run him?"

"Yes, get him out in the fresh air. Go on a case perhaps."

"Ah, well...I can try."

John comes in then. It's almost impossible to keep the two of them apart. "So, what are you two conspiring about? Some new torture for me to endure at the wedding. Want us all to wear top hats or something."

"No," Sherlock says, "But that is a good idea. Top hats go well with morning dress."

Mrs Hudson brings in the mail then, and they are preoccupied for a while with reading the RSVPs and planning the seating arrangements.

But Mary has to leave soon if she's to observe Janine at lunch. She's been watchin the security at Magnussen's offices. The membership she'd bought at the gym was surprisingly useful. It is only a few blocks from the tower, and it has lockers where she can store disguises as well as showers to remove evidence afterward. She doesn't want to miss the shift change but Sherlock is folding serviettes. She's had had enough of this. She pulls out her phone and loudly begins talking to 'Beth' before going into the kitchen. Beth is their code for let's meet secretly to talk. John enters the kitchen behind her and asks what's wrong.

"I told you to find him a new case."

"I'm trying," John says.

"You need to run him. Show him it's still the good old days." She pushes him out into the living room to confront Sherlock who has folded more than a dozen more serviettes in the few minutes they had been in the kitchen. She listens behind the door as John awkwardly calls Sherlock 'mate'. She rolls her eyes. Finally they make their way to the door, and she gives them both of them a thumbs up. Each of them thinking that leaving was their idea. She waits for the taxi to pull away before leaving.

Magnussen is surprisingly difficult to get to. His office requires a special key card to enter. There is, however, a service elevator, and although this also requires keyed entry, the floor below does not. There are windows on the edges of the hallway that can be opened to remove fumes, but they are small, and if left open, an alarm will sound.

These are things that she can work out in time. What she can't know for sure is when Magnussen will be in the building. That's where Janine comes in.

Mary sits at the coffee shop across from the office building wearing a red wig, a brown coat, and beige flats. She watches as Janine struts by. Then she tosses her cup into the trash and follows her in. Magnussen never exits on this level. He almost always enters and exits through the underground garage. His schedule is erratic with frequent meetings. Probably to torture his blackmail victims. Janine is his weakness. She knows his schedule.

When John first proposes spending his stag night alone with Sherlock, it surprises her. Why just him? But she soon agrees to it. Let them have their night. In fact, it would be best if he doesn't come home that night at all. It will give her more time to work on Janine.

She invites Janine over for a mini-hen night, and buys all of Janine's favorite alcoholic drinks. She will get her sloshed, and then weasel the schedule out of her. She will promise Janine the pick of all of the eligible men at the wedding banquet if she needs to. She will do whatever it takes. She smiles and waves at John as she prepares her strategy. Soon Magnussen will be dead, and she and John will finally have their happily ever after.