When it comes to expressing immediacy and urgency, the phrase "in a moment" might not always be the best fit. Luckily, the English language offers plenty of alternatives. One option is "right away," which conveys a sense of urgency and indicates that action needs to be taken immediately. Another synonym is "instantly," which emphasizes the speed of the response. "At once" and "immediately" are also great choices, both indicating immediate action. For a more colloquial approach, one could use "ASAP" (as soon as possible) or "pronto," which both suggest a sense of urgency. Ultimately, the choice of synonym will depend on the context, tone, and urgency of the situation.