Rocangus was a male falcon, the son of Laird Mactalon, the ruler of a falcon tribe in the Northern Mountains. His wing was fractured in a battle with a large flock of crows. He was then found by Dumble and Thrugg, who were journeying to find the Flowers of Icetor, the only cure to the sickness that was plaguing Redwall Abbey. The otter splinted Rocangus' wing for him, and the falcon joined the search.
As it turned out, the Icetor flowers grew only around the Wild King MacPhearsome's eyrie, which was located just a little bit higher in the mountains than where Rocangus' tribe roosted. With the falcon acting as navigator, the otter and the mouse set off through a forest, trying to be as quiet as possible to avoid being spotted by the resident crows.
Unfortunately, Dumble stepped on a thistle and they were set upon by dozens of crows. After a short battle, Rocangus and the others succeeded in driving the birds off; however, the crows shortly returned with a much larger force. Tammbeak, one of Mactalon's scouts, found the friends and alerted his tribe. Just as the crows were beginning to attack, the relief force arrived in the way of six falcons, one of which was Mactalon himself. In short order, the crows were driven back into a pine thicket, to the great amazement of the watchers. Rocangus and the falcons ushered Thrugg and Dumble to their home in the mountains; after the Wild King MacPhearsome agreed to bring Icetor flowers to Redwall, Rocangus accompanied Thrugg and Dumble back to the Abbey. He later regained his flight abilities at Redwall, during the feast following Dumble and Thrugg's return.