He finds and removes deadly nightshade (the cause of the poisoning), but on going back, meets an unseen monster.

The heavy carbon monoxide was an unseen monster, creeping up from all about.

For hours, they had been trailed by the sluggish, unseen monster.

Her mother, Martha Crittendon, is then attacked and killed by an unseen monster.

She gave birth to a baby in a nunnery and ends up being bitten by an unseen monster that the child was fed to.

The darkness pressed in on her, an unseen monster that sucked her breath away.

The survivors find mysterious things including polar bears, an unseen monster, and the other people living on the island, known as the "Others."

The deadly unseen monster of the canon had not attacked them.

An unseen monster was creeping up his prostrate body.

Could he have stayed on the ground with unseen monsters batting at the thin metal hull?