This is episode 4 of Hannah Montana Forever, the final season of the Hannah Montana series.

In this Hannah Montana Forever episode, De-Do-Do-Do, Da-Don't-Don't, Don't, Tell My Secret, Jackson's relationship with Siena becomes complicated when she sees Hannah Montana everywhere and suspects that Jackson and Hannah are dating. Miley struggles with the decision of whether or not to tell Siena that Hannah Montana is really Jackson's sister, Miley Stewart.

This episode of Hannah Montana Forever begins with Jackson (Jason Earles) and Siena (Tammin Sursok) playing Monopoly. Siena lands on Fifth Avenue, which has a hotel. Although she now owes Jackson $1500, she refuses to pay. They play-fight and are about to share a kiss when Siena sees a horrified Hannah Montana (Miley Cyrus) peering in the window.

Hannah rushes to her room to Lily (Emily Osment) in a panic because Siena had seen her. Meanwhile, Siena is giving Jackson a difficult time because he suspects that he is seeing Hannah Montana. Siena had "web searched" him and knows about the "Jacksannah" thing.

The whole Jacksannah thing was, of course, a misunderstanding because paparazzi had followed Hannah Montana home where Jackson had answered the door. Paparazzi jumped to the conclusion that they were dating.

Jackson tries to convince Siena that she had seen his sister Miley in the window, and not Hannah. Jackson tries to get Miley to come out by kicking her door. Miley finally comes out and tells Siena that she loves her top. Jackson tells Siena that Miley had seen her top when she was at the window.

After Siena leaves, Miley tells Jackson that he needs to stop bringing Siena to the house. Jackson refuses, arguing that Siena is the only thing that gives him the "tiniest shred of happiness." Jackson threatens to tell Siena the Hannah Montana secret.

Jackson explains that Siena's previous boyfriends had cheated on her. If Siena sees Hannah, she will assume that Jackson is just like the other cheaters. Miley promises that Siena won't see Hannah again. If she does, then Miley will tell Siena the secret herself.

Meanwhile at the pier, Robby Ray (Billy Ray Cyrus) tells Lily about his latest fishing triumph against "Bruce Gillis." He shows Lily dinner. And Lily is forced to fake excitement because he is letting her live there.

Rico (Moses Arias) badgers Al Blaine to sell his pizza place, but he refuses, saying that he is going to leave it to Al Jr., a goth guy who has the word death tattooed on his neck, and it's spelled wrong. Al explains that you can't pick your children. Rico's father should know.

Robby Ray notices that Rico is tense, so he offers to teach Rico to fish in order to help him learn to relax. Rico is still tense because after twenty minutes, he is unable to catch anything.

Lily asks Jackson to help him fold a sheet, but he refuses because he's studying. Siena gets romantic whenver he gets an A. Lily pokes fun at him, and Jackson retaliates. He farts into the sheet to show that he can fart at will.

Hannah Montana walks in, thinking that Siena is out. Siena unfortunately arrives and Miley has to hide under the ugly smelly sheet. Siena asks Miley why she is under a bedsheet and Lily covers by saying that Miley is embarrassed by how tacky she looks when compared to the well-dressed Siena.

Jackson confronts Miley at her room. He reminds her of their deal and her promise to tell Siena. Miley tries to stall, but Jackson delivers an ultimatum. She needs to tell Siena after the fitting or else. Miley realizes that she has no choice but to tell the truth.

Later at the house, Lily is nervous because if Hannah is out, then Lola is out too. Miley tells Siena that she needs to tell her something. Miley says that Siena will understand when she sees her closet. Siena thinks that Miley wants advice on how to dress better.

Miley is about to tell Siena the secret, but Siena reveals a embarrassing secret about Jackson. He still shops at Dickie Roy's Clothes for Boys. Because Siena couldn't keep Jackson's secret, Miley decides that Siena is incapable of keeping the Hannah secret.

Miley calls Jackson while he's taking an exam to tell him that Siena can't be trusted. Miley decides to tell Robby Ray, and Jackson accidentally reveals that Robby Ray is at the pier.

Robby Ray becomes increasingly frustrated that Rico is able to catch fish so easily. Meanwhile, Miley and Jackson tell him about the situation. Robby Ray says that it's Miley's decision whether or not to tell. Robby Ray is about to catch something heavy when Jackson takes the fishing rod and falls into the water.

At the house, Miley and Jackson continue to argue about the Hannah secret. Jackson points out that Lily, Oliver, and Jake know. Siena is important to Jackson and he thinks she has a right to know.

Siena enters the house and wants to know why Jackson is wet. They struggle to come up with a story when Lily enters thinking that Miley has already told the Hannah secret, but Siena takes it to mean that Jackson is still seeing Hannah Montana.

Siena is about to make a dramatic exit when Miley tells her to wait. Miley asks Jackson if he trusts Siena and he says yes. Miley offers to show Siena her closet (as Siena makes another quip about Miley's ugly clothes). Miley tells Jackson, "the things I do for you!"

After seeing the closet, Siena finally understands that Miley is Hannah Montana and that she has been pulling it off for five years. Lily comments that she has been Lola for four, but Siena doesn't know who Lola is.

As the credits roll, Rico wants a picture with his latest fishing conquest. Robby Ray leaves in frustration because he wasn't able to catch anything himself. Rico tells him to come back tomorrow because it will be his lucky day. As it turns out, Rico had hired someone to ensure that Robby Ray would not catch any fish.