Sleep stalks the rescue squad. Jaws clench. Eyelids droop. Sleep never comes, though, because everyone knows the next call is hurtling through time and space. Someone somewhere is about to jump a curb into a telephone pole or double over in cardiac arrest or succumb to his blood alcohol content and lie down in the middle of the road until a female emergency medical technician props him up, consoles him as he starts to weep in shame, and fends off a slurred marriage proposal.

The call is coming. But first:

“Ice cream,” a voice says on the PA system. “We have ice cream. Every member of the night crew please report to the kitchen.”

Bricks of Klondike Bars are dumped onto a stainless steel counter in the kitchen of the headquarters of the Bethesda-Chevy Chase Rescue Squad. “A Few Good Men” plays on the television in the next room.

July is an hour away.

The all-volunteer squad — clad in navy, spring-loaded in demeanor, attorneys and teachers and cops and students by day — nibbles on the treats to bide the time.

The call arrives. An electronic alarm sounds. A voice comes over the PA.

“Sick person run. Sick person run.”

The ambulance roars out of the station. EMT Talia Nachbi drums her hot-pink fingernails on her thigh and recalls the drunken marriage proposal from a patient.

“I said no,” she says.

She looks over her shoulder at the ambulance driver.

“This is the first time my brother has driven me,” she notes.

She is 20. Her brother, Ross Nachbi, is 23. Born and raised 10 minutes away, they’ve been EMTs with the squad since they were teenagers, when they completed a battery of training and the squad became their second family.

They find themselves in a second-floor apartment, in a bedroom, past a tray of tarnished silver and a musty set of World Book Encyclopedias, assessing the condition of a mauve-slippered 94-year-old woman who’s been vomiting. Her daughter rides with the Nachbis as they transport the woman to Sibley Memorial Hospital.

“You guys are terrific,” the daughter says as the ambulance bounces. “I admire you so much.”

Talia holds the old woman’s mottled hand — a poised, invincible college junior comforting a meek, bewildered nonagenarian, born 74 years apart, now connected by a blood-pressure gauge and zooming through the night. This is why the Nachbis and their fellow volunteers do it: to bring comfort to a person sideswiped by the unpredictable terrors of life.

The hallway of the squad’s station is lined with photos of nasty car wrecks dating back to the 1950s. Crushed Packards and mangled Fords, captions that say “Double Fatal,” drivers soaked in blood and screaming as paramedics extract them with the jaws of life.

The Wall of Death.

And yet this half-lit, two-story base is probably the calmest place in all of Montgomery County. Calm but eternally ready.

Medics and EMTs make their beds in pitch blackness upstairs, lie down in twin bunks and pretend to sleep to a lullaby of tones and alarms. Huge moths bump into overheard lights in the station garage, where the front grilles of ambulances exhale heat. Bloodied gurney belts soak in tubs of disinfectant.

That acrid smell?

Burned rubber.

That quiet electricity in the air?

Anticipation. The call is coming.

“I’m exhausted,” Ross, back from the first call of the night, says.

He brushes his teeth, changes his shirt in the musty locker room, opens the door to the darkened bunk room. His eyes barely have time to adjust before the alarm sounds.

“Whoa, good morning,” Talia says, squinting as she hurries out of the bunk room behind Ross. Brother and sister are back in the ambulance within a minute.

A fellow EMT reads the 911 printout. “Decreased consciousness” at Union Jack — i.e., a drunk outside a bar. Possible head injury.

“Ooh,” Talia says, perking up.

Several crews converge on the scene in a hurricane of red and blue lights. A man is lying on the sidewalk in front of a parking garage. He has been badly beaten. His clothes are spattered with blood. His face is lacerated, and his eyes are swollen shut. Another crew found him while responding to an unrelated assault nearby.

Brother and sister unload the gurney and rush it to the patient.

Coordinate between crews, Ross thinks. Trauma. Notify the hospital. Tell them what to expect.

Gather information, Talia thinks. Stop the bleeding. Keep the airway open.

They help load the moaning man into the ambulance and scream toward the hospital.

She wants to be a doctor someday. He’s got a daytime internship at an accounting firm but is not quite sure what he wants to do. For now, for the summer, they both wait for the call.

When they return to headquarters at 3 a.m., they head straight for the bunk room.

They rise at 7, unrested.

Talia has a summer physics class at the University of Maryland in two hours.

Then a 19-hour shift starting at 6 p.m. Saturday.

The next call is coming.