Stuart just seems like he's being manipulated; I don't want to harm him ahah.
I also had the feeling of them attempting it with April around, so April could potentially stop Mitch from killing her if he tries.
Which made me think, maybe April and Mitch have history somehow? Maybe they've met before- Especially if Mitch lives in the city. April is pretty well known as the city guardian; as that's what she acts as.

Also tempted to have Harriet go off before everything goes down, maybe her powers are bubbling through and she just has the urge to go to a place out of range of friends and her powers just bubble over; which would cause the agencies Power Radar(If they have it) Pinpoint her location but they only find it after she's come back home.