"We all raced into the den [...] We attacked, but there were too many of them, and they were too big and fierce for us. Every cat was injured. The dogs ripped Frosty to pieces, and Jester was so badly wounded that he died after we brought him back here."
Jester is one of the catsSol bands together and when Jingo tells the Clan cats about the disastrous attack on the dogs that Sol led, she explains that they all ran into the dogs' den and attacked. However, they had to retreat and Jingo mentions that Jester had been so badly wounded, he had died shortly after they brought him back to their nest.