The story mentions a tandem tricycle (which I have never seen, and sounds stupid). It occurred to me I had no idea of etymology, other than it sounded like Latin. AHD doesn't help much.
tandem

SYLLABICATION: tan·dem
PRONUNCIATION: tndm
NOUN: 1. A two-wheeled carriage drawn by horses harnessed one before the other. 2. A team of carriage horses harnessed in single file. 3. A tandem bicycle. 4. An arrangement of two or more persons or objects placed one behind the other: driving horses in tandem.
ADJECTIVE: Having two identical components arranged one behind the other: a tandem axle.
ETYMOLOGY: Latin, at last, at length. See to- in Appendix I.
OTHER FORMS: tandem —ADJECTIVE