'The Fosters' season 4 spoilers: Family throws special birthday bash for Lena, unexpected news put damper on festivities

The family gets busy preparing for Lena's '70s-themed 40th birthday bash, but surprising news may prevent it from being a truly happy gathering in the upcoming episode of Freeform's hit family drama "The Fosters" season 4.
To recap, the previous episode shown Brandon throwing a party at his and Cortney's place, only to later on realize the consequences of living with a mother and young child. Cortney finally got custody documents from her former lover while Callie uncovered distressing information when she visited her old foster homes for a senior project.
Next week's episode features the whole family as they throw a special birthday party for Lena, but things might not turn out as planned. According to the official synopsis for the episode titled "Forty," Lena is hyped to see her family becoming closely bonded again in preparation for her '70s-themed 40th birthday party. Lena's mom Dana (guest star Lorraine Toussaint, "Orange Is the New Black") pays a visit, but her arrival might not be for the best. She tells Lena about her suspicions regarding Stewart's (guest star Bruce Davison, "X-Men") behavior which could possibly put a damper on the festivities.
Callie believes that her former foster brother Kyle is wrongly convicted of murder, so she will make an effort to help him. She asks help from Aaron, and together they will track down a witness whose testimony is vital for the case. Elsewhere, Mariana showcases her skills when she joins her female STEAM club teammates as they compete to have a spot in the Regional Robotics Competition. Jude feels bad after finding out that Connor came to town without informing him while Brandon tries finding a source of income to support himself.
A promo trailer for episode 5 has been released, and the first moments of the clip features Lena as she shows off her outfit for her big day. Stef enjoys a romantic moment with her partner as they danced on stage, with the rest of the family eventually joining them.
Keep watching "The Fosters" season 4 which airs every Monday night at 8 p.m. ET on Freeform.