The itinerary includes 23h40 of transport and 3 steps.

Paris - Zurich
The step from Paris to Zurich lasts 4h10. You'll travel in a TGV Lyria.

Zurich - Zagreb
From Zurich, take the 8.40pm train to wake up refreshed in Croatia the next morning, arriving in Zagreb at 10.39am.
The step from Zurich to Zagreb lasts 14h00. You'll travel in a Nightjet operated by ÖBB.

Zagreb - Belgrade
The step from Zagreb to Belgrade lasts 5h30. You'll travel in a day bus.