The poem recounts the life of the legendary hero Lāčplēsis, chosen by the gods to become a hero of his people. His name means “Bear-slayer”, because as a young man, living as the adopted son of the Lord of Lielvārde, he kills a bear by ripping its jaws apart with his hands. At the castle of Lord Aizkrauklis, he spies on the activities of the witch Spīdala, who is under the control of the Devil, and the holy man Kangars, who is in reality a traitor plotting to replace the old gods with Christianity. Spīdala tries to drown Lāčplēsis by throwing him into the whirlpool of Staburags in the Daugava, but he is rescued by the goddess Staburadze and taken to her underwater crystal castle. There Lāčplēsis meets and falls in love with the maiden Laimdota. Shortly afterwards, Lāčplēsis becomes friends with another hero, Koknesis (“Wood-bearer”), and they study together at the Castle of Burtnieks, Laimdota's father.