There’s more than enough pre-finale tension in “Who Knows” (April 4) to go around: Between Callie’s trial, Emma’s abortion, Mariana’s memories of Ana’s neglect, the privatization plan for Anchor Bay, and Diamond doing the dirty work for her pimp, just about every secret is set to boil over.

The Mamas (Teri Polo and Sherri Saum) discuss the contents of Emma (Amanda Leighton)’s letter with Brandon (David Lambert), and mull over what to do next. Less subtle about this topic is, of course, Mariana (Cierra Ramirez) — whose secret-keeping skills are tested more than once this week. When it comes to Emma, she can’t refrain from finally admitting how upset she is to learn Emma kept such a monumental secret from her, which earns her (of course) a talking-to from Brandon… At which point Jesus (Noah Centineo) walks in.

RELATED: At long last, the romance ‘The Fosters’ has spent all season building hits — and it’s perfect

Mariana’s inability to keep a secret is going from possible character flaw to absolute strength, frankly — directly connected, as it is, with her inability to wear her heart anywhere other than on her sleeve. While keeping a confidence is an admirable quality, keeping it real is, too. For that matter, watching all the secrets blowing up in everyone’s faces makes Mariana’s forthrightness feel a hell of a lot more like the right approach: Vide her failure to keep Jude’s (Hayden Byerly) secret about Horrible Interim Principal Drew’s (Jared Ward) school privatization plans from the Mamas, which results in Monte (Annika Marks) and Lena’s full-on stakeout of a secret schoolboard meeting — obviously the coolest part of the episode.

annika marks sherri saum monte lena car fosters freeform Juggling an impressive number of grenades, Fosters sets up an intense finale

And too — there’s so much going on in Mariana’s life that honesty might also be the only policy, amid this unrelenting chaos. In one of the neatest arcs of the season, all this interaction with birth parents Ana and Gabe (Alexandra Barreto & Brandon Quinn)  is stirring up plenty of stuff for her. Watching Ana being such a good mother to Isabella isn’t quite the nailgun-to-the-head that Jesus weathered, but it’s just as painful — and when she ultimately confronts Ana in her therapist’s office, Ana doesn’t handle references to her neglect all that well. Or at all.

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For Jesus, the increased interactions with Gabe are just as fraught with tension — although Gabe scores more parenting points than Ana in this episode. While helping Gabe move into the garage, Jesus spaces out and confesses to having gone off his meds. Gabe having the sense to tell Lena about this, despite Jesus’s pleas, is the first real moment of hard parenting Gabe’s carried out thus far, and it comes with a painful consequence (as many hard parenting choices do): Jesus lashes out at Gabe about his perceived betrayal.

Brandon’s on hand to provide some comfort to Jesus, although Jesus discussing the impotence side effect of his meds leads to a heartbreaking admission that he can’t believe Emma would love him for anything but his body.

stef teri polo on the case fosters freeform Juggling an impressive number of grenades, Fosters sets up an intense finale

Then there’s the side story about Diamond (Hope Olaide Wilson) and her all-evil pimp, which starts heading in an unabashedly scary direction. Diamond’s continuing to groom one of the girls on her work detail for him — and what Stef has uncovered about this fellow, a guy named Leon Russell, goes way beyond minor crimes and misdemeanor territory, by miles. After one of his other girls got roughed up, like Diamond, the girl in question went missing. Diamond tells Stef again how scared she is, and while Stef promises Diamond a whole new identity, there’s a high probability this storyline won’t end well for Diamond — and that the fallout could be equally awful for anyone else caught in the crossfire.

Sure enough, Diamond’s pimp stops by the work detail — and Callie (Maia Mitchell) rightly smells a rat. She spies Diamond retrieving a cell phone Leon left for her in a garbage can, and puts Stef on the case. Stef instructs Callie to call her from the contraband cell to retrieve the phone’s number and return the phone to its hiding place. Now Stef’s tracking the cell phone activity between Diamond and her pimp, which is something… Alas, she’s also fighting off a sinking feeling that just maybe Diamond is one kid that can’t be saved.

And when it rains, it pours: There’s Callie’s trial for the Mamas to navigate, too.

maia mitchell adam irigoyen callie kyle fosters freeform Juggling an impressive number of grenades, Fosters sets up an intense finale

Callie is subjected to some truly tone-deaf advice from her legal team as the Mamas look on. Her lawyers insist Callie throw foster brother Kyle (Adam Irigoyen) under the bus, and play dumb about her fake car accident liability issues while batting her big eyes at the jury for good measure. Callie’s not having it — and suffice to say this scene doesn’t do anything to reverse the unflattering negative stereotype that lawyers have long endured.

After the Mamas ask the lawyers to step out of the room, Callie tells them about the phone call from Aaron she got while in Troy’s car, about Troy’s DNA being on the murder weapon. The Mamas agree this line of defense might have its upsides — although navigating around the fact that Callie obtained Doug Harvey’s DNA by breaking into his house is problematic at best. Callie proposes a cover story: She found Doug’s toothbrush in a garbage bin on the street.

All the same, Stef reveals to Callie that there’s more than just foster kid bias (and Troy’s rich kid privilege) making things look bad for Kyle in this case. Seems there’s some evidence that Kyle stole money from Martha on the day of her murder: Oh damn.

So Callie visits Kyle in prison. When she confronts Kyle about stealing money from Martha, she can’t help but ask the next obvious question: Did he kill Martha? His “What if I did?” response isn’t exactly comforting — and nor are the gang tattoos he’s recently acquired: Double damn.

When Stef sees her nemesis Detective Gray (Alex Skuby) with Doug Harvey at headquarters, there’s bad news and… Something that qualifies as only slightly less so. The bad news: Gray’s got footage of Callie breaking into Doug’s house. The slightly less bad news: At least Gray gives Stef a heads up about it, but: Triple damn.

alex skuby hugh scott detective gray doug harvey fosters freeform Juggling an impressive number of grenades, Fosters sets up an intense finale

They can’t possibly squeeze Callie’s full trial into the finale (can they?), which means we’ll likely be kept dangling about Callie’s fate until Season 5. Callie caught in the middle, between Troy’s lifelong rich frat boy privilege and Kyle’s resentment of Callie’s more recent good fortune in the foster-kid department (a resentment that just veered a little too quickly veered into pantomime villain territory in the span of one episode), is an unspeakably unfair place for such a good-hearted character to find herself. We’re bracing ourselves for one hell of a finale… And hoping, for once, for a deus ex machina to put this nightmare to bed for good.

The Season 4 finale of “The Fosters” airs Tuesday, April 11 at 8 p.m. ET/PT on Freeform — but the show returns July 11.

Posted by:Julia Diddy

Julia Diddy is a freelance writer and critic in Los Angeles.