In an interview with Entertainment Weekly, Daily explained that all of the main characters will have major storylines.
He revealed that Mike (James Denton) and Susan (Teri Hatcher) will have financial problems, while Lynette (Felicity Huffman) will give birth in "pretty scary circumstances".
"Mike and Susan are going to have some financial issues," Daily said. "They're experiencing the economic woes that much of America is experiencing and it's going to create issues in their marriage and it will lead them to make a life-changing decision in the finale."
Referring to Lynette's story, he continued: "I don't want to give too much away, but it ties into the mystery of who the Fairview Strangler is. She's going to be getting closer and closer to the identity of the person who's been terrorising the women of Fairview and then give birth, like I said, under less than ideal circumstances."
Daily added that Bree (Marcia Cross) will discover the truth about her 'son' Jeremy (Sam Page) but continued: "Unfortunately for her, he knows some shocking Van De Kamp secrets that will come back to haunt her. He has a trump card he's going to use against her."
Meanwhile, Gabrielle (Eva Longoria Parker) will try to help Angie (Drea De Matteo).
"Gaby will end up being Angie's confidante," Daily explained. "And she'll help her out as she tries to get away from her past."
Daily also ruled out the possibility of a house being blown up during the finale but revealed that there will be a "big explosion" and suggested that a character could die.
"Someone the audience has gotten to know this season [will perish]," he said.
The season finale of Desperate Housewives will air on ABC at 9pm on Sunday, May 16.