The speaker dreams of someone named Daisy, standing at the edge of a dock, alive and unharmed. The speaker walks toward her in tears, almost in a trance, and keeps repeating her name until it breaks into fragments. Then she shimmers and vanishes, and the speaker wakes up drenched in sweat.
The title calls it a nightmare, but the real pain seems to be the loss of hope. For a moment Daisy is safe, and the dream gives her back. Waking takes her away again. The poem doesn't say who Daisy is or what happened to her, though the speaker's grief suggests she is someone deeply loved and perhaps gone. The final lines blur dream and waking: "turbulent waves" threaten to pull the speaker under, and the shaking, screaming speaker can't hear a thing. The mood is panicked, raw and suffocating, a mix of longing and helplessness that doesn't let up even after waking.