Finn and the Time-Traveling Pajamas (The Finniverse Series, Bk. 2)

Finn Foley was saved from the Time Rangers by an older version of . . . himself. Now, to help his future self and find his missing father, present-day Finn is sent on an adventure with his friends Lincoln and Julep and a pair of time-traveling pajamas. There's only one problem. The pj's malfunction, sending the kids into the distant past and far-flung future, with danger waiting for them at every turn.

Saving the universe may cost Finn more than an old pair of pajamas - it may cost him his friends!