Step into My Parlor... is a mission in Marvel's Spider-Man. Mary Jane Watson calls Spider-Man to let him know she has not found the location of the Devil's Breath lab, but suspects the information may be in Norman Osborn's penthouse. With it full of Sable International soldiers, she thinks she has a better chance of sneaking in and avoiding a firefight than Spider-Man. He agrees to wait outside in case she needs backup.
Players take the role of Mary Jane as she enters the ground floor. With the elevators on lockdown, she needs to access the security room first. To do so, players need to talk with several of the tenants in order for them to get riled up, causing a diversion. Once in the hall, players find a stun gun, and this becomes the first mission Mary Jane can be used in combat by sneaking up behind guards and stunning them. After stunning the second guard, the security room is to the left.
Once the elevator is unlocked, players proceed back to the main foyer, sneaking into the elevator just after Silver Sable and Norman Osborn exit. In the penthouse, players pick up a mask on the table near blueprints and, with Mary Jane wearing it, can detect a hidden door in the wall. The clue to the code for the revealed keypad can be found on the dining room table, which then requires players finding the key to Harry Osborn's room. This can be found in the picture frame that shows only his mother, in the same room players can find the picture of Norman and Otto Octavius.
Accessing Harry's room, players find his journal, which supplies his departure date for "Europe" (in reality, entering treatment). This date is also the code for the keypad. Before she can access the hidden room, Silver Sable and Norman return. After an argument, players need to sneak past the guards to use the access code.
In the secret lab, players need to deduce the location of the Devil's Breath lab using the large computerized map in the center of the room. It will end up being the building the furthest to the right. Mary Jane then access some records and discovers the truth of Mister Negative's origin: that Norman and Otto were working on GR-27 some time ago, and Norman rushed ahead with human trials by giving a young Martin Li the serum when his parents came in for a consultation. Li exhibits his trademark "negative" abilities, appearing to kill both his parents. Mary Jane begins downloading the information, but is startled by a container that holds a jumping spider, causing one of the nearby glass containers to shatter.
Silver Sable enters and Mary Jane holds still in her hiding spot, despite one of the freed spiders crawling over her. Once Sable leaves, players need to sneak out of the lab and to the balcony. As she takes out the last guard on the balcony, he fires a round, alerting the other soldiers. With no other recourse and with Silver Sable and her men approaching, she leaps off the edge, to be caught by Spider-Man below.