Morgan, for all of her general timidity toward the outside world, was positively fearless when it came to amusement park rides—when she was younger she used to stand on tiptoe to meet the requisite height minimum for the roller coasters—and she and Katie spent most of the drive to the park on their phones, looking through Canobie’s Web site so Morgan could tell Katie what was what. Wipeout was overrated. The pirate ship was only worthwhile if you were at either end. The Corkscrew Coaster was more jarring than scary, but Starblaster was pretty good. Yankee Cannonball was old-fashioned but fun, and the newest roller coaster, Untamed, was the best.

Here Cam turned from the front seat to deliver a history lesson on how the Yankee Cannonball was the oldest continuously running wooden roller coaster in the country and how it was moved in 1936 from Waterbury, Connecticut, and how they had to shorten each section by six inches to get it into the space where it now resided. Alexa glanced in the rearview mirror, expecting to see the girls’ eyes glazing over with boredom, but instead they both seemed riveted. They were staring at Cam like he was solving for them the riddle of the Sphinx, and Alexa remembered that these girls were young and neither one had an older brother or a father. The attention of a fairly charming and, it should be noted, pretty good-looking example of the male species was probably exotic enough to be entrancing.

Once inside the park, a wave of nostalgia washed over Alexa. She still had a photo of herself with Destiny and Caitlin standing in front of the Boston Tea Party at about the age Morgan and Katie were now, when life was easier to navigate. Their T-shirts were soaked—you got positively doused on the Boston Tea Party—and they were smiling hard, with the July sunlight glinting off their braces.

Of course the girls wanted to go off on their own. Alexa hesitated, thinking about the bad men. She glanced around. The park was getting crowded.

“They’ll be okay,” Cam said. “I mean, if you’re worried, we can stay with them. But I think they’ll be fine.” He was wearing a St. Michael’s baseball cap, but other than that he was surprisingly, refreshingly free of spirit wear.

Morgan said, “Pleeeeeasssse,” and practically went down on her knees on the asphalt to beg, and Katie gave Alexa puppy dog eyes.

“Okay,” said Alexa finally. “But if anybody bothers you, you scream as loud as you can, got it?” Morgan opened her mouth as if to demonstrate and Alexa said, “Not now! Only if somebody bothers you.”