Slipback
Painfully bad attempt at Douglas Adams type humor. The plot varies from non-existent to baffling, the Doctor and Peri don't actually seem to do anything that influences the plot, there is a ton of obvious padding to get it to the Target novelization 150 page limit, when the plot actually shows up it contridicts something from a Fifth Doctor story ( which wouldn't be so bad but both stories were written by the same guy) and for a humor novel, it isn't terribly funny.
The two policemen that keep capturing Peri and then can't decide weither or not to shoot her were worth a chuckle.