Cat Flaps

Enemy at the Cat Flap
(Space Police #5)
by David Blake (2018)
The Mayor of London’s cat has gone missing, and it’s up to Capstan and Dewbush to find it. But when they discover an ancient cat flap that for centuries has been used as a gateway to another planet, what starts off as a bog-standard missing pet case soon becomes something altogether more sinister.

Not much to add without giving away the plot. Yet again Capstan & Dewbush prove themselves to be the Laurel & Hardy of future crime fighting. David Blake just keeps writing new books without any reduction in quality.