The speaker is looking for Cometina, someone who disappeared in November and came back for a single day in April. Cometina could be a person, a pet, or even something more elusive. The poem never says. Other people offer theories: she took a train to Australia, she ran to Africa. The speaker brushes these off as unlikely, but admits that doubting them doesn't help, because they still have no idea where she is.
The mood is a mix of worry, stubbornness, and dark humor. By January the speaker has been waiting for months, and when they point out that no one could run across an ocean, they are dismissed as crazy. The final lines turn the joke on everyone: there is no train to Australia at all. The speaker has quietly noticed how absurd the stories are, yet is the one treated as unreasonable. Underneath the wry tone is a sense of loss and of not being believed.