The 29-year-old took two wickets in two balls to keep England's hopes of victory alive, as India ended day three of the second Test with a 145-run lead.
"We're going to go hard in the morning because this is still a good cricket wicket and if we can get a few more wickets, we'll fancy our chances," Plunkett is quoted as saying by BBC Sport.
"It's a good wicket, they always get better at Lord's. If someone gets in, you can score quickly. I think we can chase around 270."
The right-handed bowler made his England Test debut in 2005.