Callie and AJ are in for a big surprise in the upcoming episode of "The Fosters" season 4.

Both Callie and Brandon have already moved on with their lives after their failed relationship, but it looks like tension will still arise between them in episode 7.

The episode will follow Callie as she gets caught in a difficult situation with her new boyfriend, AJ.

According to TV Guide, Brandon and his father Mike will arrive home earlier than usual, only to know that a surprise is actually waiting for them inside. Some speculate that the surprise could be Callie and AJ doing something really intimate, knowing that nobody's around the house. Things will get totally awkward because, of all people, it is Brandon who will witness their lovemaking.

The episode will also see Stef tell her ex-husband what Brandon has been doing with his life. She will tell him about his financial problems, and how he has resorted to any means just to get money. In the previous episode, Stef even found out that Brandon took the SAT for someone else and was paid for it. He also infuriated Stef and Lena when he gave his settlement money to Cortney. Episode 7 will see what Mike will do to knock some sense into Brandon.

Episode 7 will also follow Mariana as she spirals out of control. She will take her brother's ADHD medication just to cope with the pressure brought by her relationship with her troubled boyfriend Nick.

"The Fosters" season 4 airs every Monday, 8:00 P.M. on Freeform.