Learn Farsi: شرور گروگان گرفت، اما من ردیابی‌اش کردم. - The villain took a hostage, but I tracked him.

This highlights our current lesson on compound verbs. The compound verb here is ردیابی کردن (to track). Instead of using a separate pronoun for the direct object, Farsi often attaches an object enclitic—here, اش meaning 'him'—directly to the noun part of the compound verb. So ردیابی‌اش کردم structurally acts like 'I did his tracking'.

Could I just say او را ردیابی کردم instead of splitting the compound verb?

Yes, you could say اما من او را ردیابی کردم, and it means the exact same thing. However, inserting the enclitic into the middle of the compound verb (like ردیابی‌اش کردم) is extremely natural and heavily used in both spoken and written Farsi, so mastering this structure is a major step forward at the B2 level.

Why isn't there a را after گروگان if it's the object of the verb 'took'?

Because گروگان (hostage) is indefinite or non-specific here—the villain took 'a' hostage, not 'the' hostage. The object marker را is only used for definite direct objects. Furthermore, گروگان گرفتن functions essentially as a compound verb meaning 'to take hostage', making را unnecessary.

I learned شرور as an adjective meaning 'wicked' or 'evil'. Is it functioning as a noun here?

Yes, Farsi frequently drops the noun and uses adjectives independently to refer to people who possess that quality. Just as English sometimes does with phrases like 'the wicked', Farsi uses شرور here as the subject of the sentence to simply mean 'the villain' or 'the evil person'.