Hmmm… There seems to be a bit of trouble with tenses here.
Because some of this example is already in past-tense, and because I don’t like present tense (far from “creating a sense of immediacy and intimacy,” the way some writers and readers claim it does, it usually feels artificial and even gimmicky to me), I’m going to make all of it past tense.
In addition to changing verb tenses, add a comma after suitcase in the second sentence and change the ellipsis (at least it’s a real one!) at the end to a period.
You just got back from a trip and opened your suitcase. You quickly discovered that this was not your suitcase, and something horrible was inside.