X-Men #8 opens with Professor X still gone and Scott in charge. He's driving himself and the rest of the team hard, as is his wont. And although we've seen isolated examples of anti-mutant hysteria before, we get our best one yet, where Beast rescues a child trapped up on top of a water tower, and for his trouble gets mobbed. Together, that's enough for Beast - he quits the X-Men (and not for the last time) - and becomes a heel in pro wrestling! As with the coffee bar last issue, this is an environment he can show a bit more of himself, and have it assumed to be a performance by others, making it a kind of mutant drag. Scott takes it badly, realising that Beast quitting the X-Men means he as failed as leader (something that will also hit hard in several hundred issues from now). He contacts Xavier, who is busy in Europe on a mission we will learn more about in issue #9.
The X-Men Season One OGN by Hopeless and McKelvie (coming out later this month) is apparently based around this issue, and as Hopeless points out it's an important moment in Beast's character development, as he uses science to solve the plot for the first time (although he's been portrayed as a bookworm since #3). I will make no attempt to further summarise the events, but will note it is as mad as a hat of frogs.