More humor with a British accent—from the prolific Holt, a sequel to The Portable Door (2004) and fourth in a series set in the same science-fantasy universe.
A Portable Door is like a magical ace of trumps: Not only does it give the user access to anywhere, including past and future, but it also beats any other opposing magic. Young Frank Carpenter, despite a total lack of magical ability, inherited a Door from his parents (they're not dead, but hiding in a private universe). Frank did have the advanced mathematical knowhow necessary to use the Door effectively, however, so he approached insurance mogul George Sprague and proposed that when George was faced with paying a large claim, Frank—for a modest ten percent—would simply go back in time and make the event not happen. The arrangement proves hugely profitable to both parties. Meanwhile, loyal but harassed pest control operative Emily Spitzer visits a bank vault with orders to kill the dragon inconveniently slumbering there. Unfortunately, the dragon's already incinerated all the valuable paper, leaving only a small cardboard tube that Emily tucks absent-mindedly into her sleeve, before being ordered out again by her sarcastic and infuriating boss Colin Gomez to rescue an old lady's treed cat. Inexplicably, Emily falls off her magic ladder and dies. George, confronting another large payout (Emily's employers insured her heavily) hires Frank to reverse the event. But this time Frank fails. Repeatedly. Emily, it seems, is the victim of a Better Mousetrap, guaranteed lethal in all situations. But who would want to kill Emily and why? Frank decides to find out.
Funny and intriguingly complex—a difficult juggling act that Holt carries off with aplomb.