I deleted in order because those words are “filler words,” unnecessary and clunky.
Replace the comma after begin with a period.
The death whistle is blown to help the deceased journey to the underworld.
The ceremony is about to begin. The whistle is missing.
This is another example of how present tense can go wrong. Is blown says this is happening right now (and also, this actually is passive voice), but obviously it can’t be happening right now because the whistle is missing.
Y’know how, in past-tense narration, there are some things more past than others (things that had happened, as compared to things that happened)? Well, even in present-tense narration, you have things that happened before the “right now” of the story, and those things require past-tense verbs.
(If you want all the jargon, all the time, get your own copy of The Chicago Manual of Style and read it. I’m just trying to explain the mechanics of writing in a way that makes sense to everyone.)