In Ciri’s Footsteps is the umbrella main quest of Act I in The Witcher 3. It tracks Geralt’s progress through the three big storylines that open after Imperial Audience: the Bloody Baron and the Crones in Velen, Triss and Dandelion in Novigrad, and Yennefer in Skellige.
Emhyr’s spies have gathered reports from all three places. In Velen, they were fairly sure Ciri had been there and might still be. From Novigrad came unconfirmed sightings, and from Skellige nothing concrete except an explosion of magical energy on one of the isles that almost certainly involved her. Geralt’s job is to follow up on all of it.
As he works through each region, he confirms that Ciri really did pass through all three places, and in the end he finds someone who was travelling with her until recently. The catch is that this companion, known only as Uma, is under a curse that has made him the ugliest and most maddeningly stupid creature imaginable. The quest completes once every main storyline in Velen, Novigrad and Skellige is done, and leads straight into Ugly Baby.