Mrs. Swift, a slender, petite woman, tried not to show concern when she saw the boys, bruised and disheveled.  “I’m so thankful you’re both safe!” she murmured.

Blond, blue-eyed Sandy, who was a year younger than Tom, had invited her friend Phyllis Newton to the house for dinner.  Phyl, a pretty, dark-haired girl, was the daughter of Mr. Swift’s long-time friend and business associate, “Uncle Ned” Newton.  The two girls were as much upset as Tom’s mother.

Tom laughed.  “We’re not stretcher cases,” he said.  “Why, one of the ambulance doctors checked us out.”

Bud groaned.  “Why did you have to go and spoil it?” he complained jokingly.  “I was all set for Sandy’s cool soothing touch on my fevered brow!”

Mr. Swift came into the living room just then and told Tom how worried Mrs. Swift and Sandy had been.  “I tried to assure them that you and Bud can take care of yourselves in any crisis.”  He smiled guiltily as he added, “But I must admit I was more than a little concerned myself.”

As Tom grinned, the resemblance between him and his father was very evident.  Both had the same clean-cut features and deep-set blue eyes, although Tom Jr. was lankier and taller.

After the two boys had showered and changed their clothes, Mrs. Swift served them a delicious, hot meal.  While they ate, Mr. Swift managed after some difficulty to get a call through to the Harkness Hospital.  His face was grave as he hung up.

“Mark Faber is not expected to live,” the elder inventor reported.  “A pity.  He’s a great scientist.”

Tom nodded unhappily.  Sandy, to take her brother’s mind off the disaster, said, “Dad, tell Tom and Bud about the visitor who’s coming.”

“A visitor?” Tom looked at his father.

“From another planet,” Mr. Swift revealed.

Both boys were amazed and excited.  “Wow!” Bud gasped.  “Male or female?  Human or animal?”

Mr. Swift’s eyes twinkled.  “None of those,” he replied as the boys stared, mystified.

CHAPTER II

THE MYSTERIOUS HITCHHIKER

Tom and Bud were bursting with curiosity.  Although the Swifts had been in radio contact with creatures from outer space for many months, this was the most exciting news yet!

On one occasion, the unknown beings had moved a small asteroid—­the phantom satellite Nestria—­into orbit about the earth.  Later they had sent strange samples of the animal life of their planet, aboard orbiting missiles, to be studied by the Swifts.  They had also helped Tom, Bud, and Mr. Swift a number of times when their lives were at stake while on daring voyages beyond the earth.  What was their latest intention?

The telephone rang and Sandy went to answer it.

“For Pete’s sake, Dad,” Tom pleaded, “don’t keep us in suspense!  Who or what is this visitor?”

Mr. Swift smiled at the boys’ baffled expressions.  “The fact is that a message came through today that—­”