The sixth episode in this STEM-themed caper brings at least one story arc to a conclusion. Twin gadgeteers Nick and his sister, Tesla, are reunited with their captive scientist parents just in time to save the world (or at least the president) from a mad superpatriot with an orbiting microwave weapon. Along with plenty of clever sleuthing, science talk, and silly banter, this exploit is punctuated by several sets of specific instructions for constructing solar-powered doodads from inexpensive materials cluding a hot dog cooker and a wheeled minirover at feature in the tale. Frequent illustrations will be included in the finished copies.

Young inventors Nick and Tesla find a new lead in the search for their missing parents. After discovering a traitorous agent, the twins are kidnapped and held hostage to force their parents to convert their solar-powered invention into a weapon. As usual, this sixth series entry achieves an enjoyable balance of mystery, humor, and DIY science projects. Two-color illustrations are included.

Gr 3–6— Twin kid inventors Nick and Tesla are back in their sixth, and likely final, mystery, which sees them dodging spies while trying to locate their missing parents, who may be part of a top-secret, space-based solar-power project with the government. Spending the summer in Half Moon Bay with their eccentric and somewhat bumbling Uncle Newt, they have so far not been fruitful in finding their parents, but this time, all hands are on deck trying to unravel the clues and figure out who the traitors or double agents are and whom they can trust before it's too late. The authors once again intersperse kid-friendly instructions to build the solar-powered gadgets featured in the story including a hot dog cooker and a nighttime signal cannon that fires illuminated ping-pong balls. The twins' friends Silas and DeMarco are back, hoping to help in the quest. Science lovers, mystery hounds, and fans of the series will want to follow along to the satisfying conclusion. Humorous footnotes remind readers of what they have missed in the prior books, which aren't necessary to understand this tale but are certainly helpful. VERDICT Just the right amount of suspense, action, and science to entice a wide variety of readers.— Michele Shaw, Quail Run Elementary School, San Ramon, CA