Your first goal is to get out of the basement.  Your conscience, such as it is, won't let you leave as long as you think the service will be over soon.  Examining the book from which Stu is chanting will disabuse you of that notion real quick.

x stu
x book
u

Upstairs, take everything that isn't nailed down, like a good adventurer.

x cans
get cans
x boxes
open boxes
get paper
open fridge
get bag

Now you stumble across the problem: there's an adventurer who is about to foil your cult's plans.  There's also a locked door to deal with eventually.

n
x walter
smell walter
w
x ark
x teens
buy bacon

Continue exploring the restaurant.  Examining the chandelier also reveals something important -- the theft was captured on film.

n
x chandelier
x camera
n
sw
x trunk
x flashlight
get flashlight
x dvds
get dvds
x car
x footprints
enter car
ne
w

Now you need to talk to your friend Jeff.  It seems Jeff is in pretty dire straits himself.  You'll need to find a way to free him while not getting eaten by the beetle.  If you consult the tomes downstairs, you'll learn that the beetle is easily distracted by sudden, random movements, and especially by the color red.

out
get balloon
n
x counter
x oval
x beetle
x bookcase
open door
d
x tomes
consult tomes about beetle
get glove
u

You can defeat the beetle by making use of the balloon.

inflate balloon
break oval
drop balloon
close door

With Jeff freed, you can pump him for information.  Might as well grab that monitor, too, while you're here.

z
bump fist
a how
a beetle
a young woman
t heart
a monitor
get monitor
s
enter car

Jeff mentioned that the young woman knew about Carver's Cave.  There were also muddy footprints on your car.  Better check out the cave.

e
ne
out
d
n

Hm, can't get in.  Friction is your enemy here.  The greasy sheets of wax paper come in handy.

remove robe
grease me with paper
turn on flashlight
n

The serpent's blood has a very useful quality: it burns through metal.  This might help with your locked door problem.  To get the blood, you'll need a suitable container (the ziploc bag) and the latex glove.

x serpent
x blood
wear glove
get blood
s

You can't leave with the bag.  So perhaps you and the bag can leave separately.  The current in the water will help you out.  Make sure you close the bag first.

x pool
close bag
put bag in pool
s
d
get bag
u
u
enter car
sw

Now to finally get in that office door.  You can't unlock it, but you can use the serpent's blood to burn your way through.

out
s
s
x lock
put bag in lock
squeeze bag
w

The security system can tell us who the pesky investigator is.  Make sure to print a picture and grab it.

connect monitor
press rewind
think
press print
get image
e
n
n
enter car


Now to inquire with your ex-girlfriend about the woman in the picture.  Your ex is a little brusque, but is still helpful, provided you return her DVDs.

n
out
ring bell
x sam
a how
a hijab
a seeing
a uma
a woman
t spell
a dvds
give dvds to sam
enter car
sw

You have the ingredients for Jeff to cast the spell.  Only one hitch: at the crucial moment, you sneeze, ruining the ritual.  The solution?  Raise your hood.

out
n
give hairclip to Jeff
give image to Jeff
wear hood

So the adventurer's in a synagogue.  You will need a ticket to follow her inside.  (This is 100% true on Yom Kippur, incidentally).  Tickets are not for sale, so you'll need to steal one.  That volunteer accepting bags of canned goods has one dangling from an unworn jacket.  You just need to distract her.  Following the unwitting example of another donor, you can sabotage the bag, forcing her to chase after cans that are rolling down the street.

x van
x volunteer
x jacket
s
w
n
e
se
get bag
put cans in bag
rip bag
nw
w
give bag to volunteer
get ticket


Now we just give the ticket and enter the chapel.  We scan the crowd a few times to find Leah, until we spot her.  She's got a satchel with her, and inside is the Heart!  Just take it, and your nightmare is over...

s
give ticket to woman
x crowd
x crowd
x crowd
x leah
x satchel
get heart

After this, there are several endings possible.  You can try doing nothing, giving the Heart to Stu, eating the Heart, escaping to the south with or without the Heart, and finally, blowing the horn.