My uncle forged a will illegally a long time ago. what can i do?

someone took my uncle down to the place and he signed my uncle's will. My uncle had ahlzheimers and when he did this. They put a Target store on my granddads property. the money was supposed to go to my uncle and mom. I really would like a lawyer's opinion on this. I know the land is worth over 2 million. I need help. so can someone help me with this. I guarantee that his name is forged.