Sloppy, and vague. Young; how young? Five, fifteen, twenty-five? They’re all young, it’s a relative term. What is an experimental farm? Why would a farm be heavily guarded; soybean rustlers? Does it matter it’s in south Texas vs. north or west, or Texas at all? Why the need to leave just because coworkers disappear? Ever have a job where someone just isn’t there one day? People quit, get fired, don’t show up; there’s nothing sinister about it. If there is, give us a clue.

You need to provide specifics regarding what this story is actually about, do it in a single sentence without halting in the middle to update it, and without being TOO specific when not necessary. A logline is just to make someone want to read more; it doesn’t matter at this point they’re brother and sister…just use siblings. We don’t need to know it’s Texas, or even the U.S.; only provide personal detail that helps define their conflict.

A pair of illegal immigrant siblings must escape a work farm when it becomes clear the company performs dangerous experiments on its employees.

Not very poetic, but I’m sure you can improve on it. The point is, it sets up the two leads while defining? – in broad strokes, but with clear details – their situation, their opposition, and their downfall if they fail. The fact they’re illegal shows they need whatever work they can get, but also how they can’t go to the authorities with whatever evidence they have. Plus it highlights the David & Goliath aspect of two kids facing down an entire evil organization.

Protagonist, antagonist, conflict, stakes…that’s all a logline needs. The rest goes in a script, treatment, or synopsis.