Dreams dictionary: Plunge
Dreams dictionary: Interpretation 1
To dream that you are plunging into something indicates that you are facing some uncertainty in your waking life. You need to be willing to take a risk in order to move forward toward your goals.
Dreams dictionary: Interpretation 2
To dream that something is plunging in your chest or someone else's chest suggests that you are ignoring some obvious truth. You are refusing to acknowledge and confront the truth.